sigpro/docs/assets/api_signals.md.CrW68-BA.js

import{_ as i,o as a,c as n,ae as h}from"./chunks/framework.C8AWLET_.js";const g=JSON.parse('{"title":"Signals API 📡","description":"","frontmatter":{},"headers":[],"relativePath":"api/signals.md","filePath":"api/signals.md"}'),k={name:"api/signals.md"};function l(t,s,p,e,E,r){return a(),n("div",null,[...s[0]||(s[0]=[h(`<h1 id="signals-api-📡" tabindex="-1">Signals API 📡 <a class="header-anchor" href="#signals-api-📡" aria-label="Permalink to &quot;Signals API 📡&quot;">​</a></h1><p>Signals are the heart of SigPro&#39;s reactivity system. They are reactive values that automatically track dependencies and notify subscribers when they change. This enables fine-grained updates without virtual DOM diffing.</p><h2 id="core-concepts" tabindex="-1">Core Concepts <a class="header-anchor" href="#core-concepts" aria-label="Permalink to &quot;Core Concepts&quot;">​</a></h2><h3 id="what-is-a-signal" tabindex="-1">What is a Signal? <a class="header-anchor" href="#what-is-a-signal" aria-label="Permalink to &quot;What is a Signal?&quot;">​</a></h3><p>A signal is a function that holds a value and notifies dependents when that value changes. Signals can be:</p><ul><li><strong>Basic signals</strong> - Hold simple values (numbers, strings, objects)</li><li><strong>Computed signals</strong> - Derive values from other signals</li><li><strong>Persistent signals</strong> - Automatically sync with localStorage/sessionStorage</li></ul><h3 id="how-reactivity-works" tabindex="-1">How Reactivity Works <a class="header-anchor" href="#how-reactivity-works" aria-label="Permalink to &quot;How Reactivity Works&quot;">​</a></h3><p>SigPro uses automatic dependency tracking:</p><ol><li>When you read a signal inside an effect, the effect becomes a subscriber</li><li>When the signal&#39;s value changes, all subscribers are notified</li><li>Updates are batched using microtasks for optimal performance</li><li>Only the exact nodes that depend on changed values are updated</li></ol><h2 id="initialvalue" tabindex="-1"><code>$(initialValue)</code> <a class="header-anchor" href="#initialvalue" aria-label="Permalink to &quot;\`$(initialValue)\`&quot;">​</a></h2><p>Creates a reactive signal. The behavior changes based on the type of <code>initialValue</code>:</p><ul><li>If <code>initialValue</code> is a <strong>function</strong>, creates a computed signal</li><li>Otherwise, creates a basic signal</li></ul><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Basic signal</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> count</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
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<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Computed signal</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> firstName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;John&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> lastName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Doe&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> fullName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> \`\${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">firstName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">} \${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">lastName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}\`</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span></code></pre></div><h2 id="📋-api-reference" tabindex="-1">📋 API Reference <a class="header-anchor" href="#📋-api-reference" aria-label="Permalink to &quot;📋 API Reference&quot;">​</a></h2><h3 id="basic-signals" tabindex="-1">Basic Signals <a class="header-anchor" href="#basic-signals" aria-label="Permalink to &quot;Basic Signals&quot;">​</a></h3><table tabindex="0"><thead><tr><th>Pattern</th><th>Example</th><th>Description</th></tr></thead><tbody><tr><td>Create</td><td><code>const count = $(0)</code></td><td>Create signal with initial value</td></tr><tr><td>Get</td><td><code>count()</code></td><td>Read current value</td></tr><tr><td>Set</td><td><code>count(5)</code></td><td>Set new value directly</td></tr><tr><td>Update</td><td><code>count(prev =&gt; prev + 1)</code></td><td>Update based on previous value</td></tr></tbody></table><h3 id="computed-signals" tabindex="-1">Computed Signals <a class="header-anchor" href="#computed-signals" aria-label="Permalink to &quot;Computed Signals&quot;">​</a></h3><table tabindex="0"><thead><tr><th>Pattern</th><th>Example</th><th>Description</th></tr></thead><tbody><tr><td>Create</td><td><code>const total = $(() =&gt; price() * quantity())</code></td><td>Derive value from other signals</td></tr><tr><td>Get</td><td><code>total()</code></td><td>Read computed value (auto-updates)</td></tr></tbody></table><h3 id="signal-methods" tabindex="-1">Signal Methods <a class="header-anchor" href="#signal-methods" aria-label="Permalink to &quot;Signal Methods&quot;">​</a></h3><table tabindex="0"><thead><tr><th>Method</th><th>Description</th><th>Example</th></tr></thead><tbody><tr><td><code>signal()</code></td><td>Gets current value</td><td><code>count()</code></td></tr><tr><td><code>signal(newValue)</code></td><td>Sets new value</td><td><code>count(5)</code></td></tr><tr><td><code>signal(prev =&gt; new)</code></td><td>Updates using previous value</td><td><code>count(c =&gt; c + 1)</code></td></tr></tbody></table><h2 id="🎯-basic-examples" tabindex="-1">🎯 Basic Examples <a class="header-anchor" href="#🎯-basic-examples" aria-label="Permalink to &quot;🎯 Basic Examples&quot;">​</a></h2><h3 id="counter-signal" tabindex="-1">Counter Signal <a class="header-anchor" href="#counter-signal" aria-label="Permalink to &quot;Counter Signal&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> count</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 0</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 5</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">prev</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> prev </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 6</span></span></code></pre></div><h3 id="object-signal" tabindex="-1">Object Signal <a class="header-anchor" href="#object-signal" aria-label="Permalink to &quot;Object Signal&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
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<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;John&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  age: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">30</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  email: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;john@example.com&#39;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Read</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().name); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// &#39;John&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Update (immutable pattern)</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  age: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">31</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Partial update with function</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">prev</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  ...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">prev,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  email: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;john.doe@example.com&#39;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}));</span></span></code></pre></div><h3 id="array-signal" tabindex="-1">Array Signal <a class="header-anchor" href="#array-signal" aria-label="Permalink to &quot;Array Signal&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> todos</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Learn SigPro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Build an app&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Add item</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(), </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Deploy to production&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Remove item</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">_</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!==</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">));</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Update item</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">todo</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ?</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Master SigPro&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> todo</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">));</span></span></code></pre></div><h2 id="🔄-computed-signals" tabindex="-1">🔄 Computed Signals <a class="header-anchor" href="#🔄-computed-signals" aria-label="Permalink to &quot;🔄 Computed Signals&quot;">​</a></h2><p>Computed signals automatically update when their dependencies change:</p><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> price</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> quantity</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> tax</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0.21</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Computed signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> subtotal</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> price</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> quantity</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> taxAmount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> tax</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> taxAmount</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">total</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 24.2</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">price</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">15</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">total</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 36.3 (automatically updated)</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">quantity</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">total</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 54.45 (automatically updated)</span></span></code></pre></div><h3 id="computed-with-multiple-dependencies" tabindex="-1">Computed with Multiple Dependencies <a class="header-anchor" href="#computed-with-multiple-dependencies" aria-label="Permalink to &quot;Computed with Multiple Dependencies&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> firstName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;John&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> lastName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Doe&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> prefix</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Mr.&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> fullName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">  // Computed signals can contain logic</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> name</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> \`\${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">firstName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">} \${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">lastName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}\`</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> prefix</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">?</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> \`\${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">prefix</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">} \${</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">name</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}\`</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> name;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">fullName</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// &#39;Mr. John Doe&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">prefix</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">fullName</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// &#39;John Doe&#39;</span></span></code></pre></div><h3 id="computed-with-conditional-logic" tabindex="-1">Computed with Conditional Logic <a class="header-anchor" href="#computed-with-conditional-logic" aria-label="Permalink to &quot;Computed with Conditional Logic&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ role: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;admin&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, permissions: [] });</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isAdmin</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().role </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;admin&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> hasPermission</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  isAdmin</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">||</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().permissions.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">includes</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;edit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">hasPermission</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// true</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ role: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;user&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, permissions: [</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;view&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">] });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">hasPermission</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// false (can&#39;t edit)</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ role: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;user&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, permissions: [</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;view&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;edit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">] });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">hasPermission</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// true (now has permission)</span></span></code></pre></div><h2 id="🧮-advanced-signal-patterns" tabindex="-1">🧮 Advanced Signal Patterns <a class="header-anchor" href="#🧮-advanced-signal-patterns" aria-label="Permalink to &quot;🧮 Advanced Signal Patterns&quot;">​</a></h2><h3 id="derived-state-pattern" tabindex="-1">Derived State Pattern <a class="header-anchor" href="#derived-state-pattern" aria-label="Permalink to &quot;Derived State Pattern&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Shopping cart example</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> cart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Product 1&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, quantity: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Product 2&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">15</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, quantity: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Derived values</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> itemCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.quantity, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> subtotal</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (item.price </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.quantity), </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> tax</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0.21</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> tax</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Update cart</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Product 3&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">20</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, quantity: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// All derived values auto-update</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">itemCount</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// 4</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">total</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// (10*2 + 15*1 + 20*1) * 1.21 = 78.65</span></span></code></pre></div><h3 id="validation-pattern" tabindex="-1">Validation Pattern <a class="header-anchor" href="#validation-pattern" aria-label="Permalink to &quot;Validation Pattern&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> email</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> password</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> confirmPassword</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Validation signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isEmailValid</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> value</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> email</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> /</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#DBEDFF;">@</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#22863A;--shiki-light-font-weight:bold;--shiki-dark:#85E89D;--shiki-dark-font-weight:bold;">\\.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+$</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">/</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">test</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(value);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isPasswordValid</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> value</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> password</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> value.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> &gt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 8</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> doPasswordsMatch</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  password</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> confirmPassword</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isFormValid</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  isEmailValid</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&amp;&amp;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> isPasswordValid</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&amp;&amp;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> doPasswordsMatch</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Update form</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">email</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;user@example.com&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">password</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;secure123&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">confirmPassword</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;secure123&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">isFormValid</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// true</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Validation messages</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> emailError</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  email</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&amp;&amp;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> !</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">isEmailValid</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">?</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Invalid email format&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;&#39;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span></code></pre></div><h3 id="filtering-and-search-pattern" tabindex="-1">Filtering and Search Pattern <a class="header-anchor" href="#filtering-and-search-pattern" aria-label="Permalink to &quot;Filtering and Search Pattern&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> items</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Apple&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, category: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;fruit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Banana&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, category: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;fruit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Carrot&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, category: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;vegetable&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Date&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, category: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;fruit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> searchTerm</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> categoryFilter</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;all&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Filtered items (computed)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> filteredItems</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  let</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> items</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">  // Apply search filter</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">searchTerm</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> term</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> searchTerm</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">toLowerCase</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    result </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      item.name.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">toLowerCase</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">includes</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(term)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    );</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">  // Apply category filter</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">categoryFilter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!==</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;all&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    result </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      item.category </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> categoryFilter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    );</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Stats</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> fruitCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  items</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.category </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;fruit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">).</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> vegCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  items</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.category </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;vegetable&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">).</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Update filters</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">searchTerm</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filteredItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i.name)); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// [&#39;Apple&#39;, &#39;Banana&#39;, &#39;Carrot&#39;, &#39;Date&#39;]</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">categoryFilter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;fruit&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filteredItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i.name)); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// [&#39;Apple&#39;, &#39;Banana&#39;, &#39;Date&#39;]</span></span></code></pre></div><h3 id="pagination-pattern" tabindex="-1">Pagination Pattern <a class="header-anchor" href="#pagination-pattern" aria-label="Permalink to &quot;Pagination Pattern&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> allItems</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">Array</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">100</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">).</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">keys</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()].</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> \`Item \${</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> +</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}\`</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">));</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> currentPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> itemsPerPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Paginated items (computed)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> paginatedItems</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> start</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> itemsPerPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> end</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> start </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> itemsPerPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> allItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">slice</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(start, end);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Pagination metadata</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> totalPages</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  Math.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">ceil</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">allItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> /</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> itemsPerPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">())</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> hasNextPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> totalPages</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> hasPrevPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> pageRange</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> current</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> totalPages</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> delta</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  let</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> range </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [];</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  for</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">let</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Math.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">max</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, current </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> delta); </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">       i </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Math.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">min</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(total </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, current </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> delta); </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">       i</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">++</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    range.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">push</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(i);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (current </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> delta </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) range </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;...&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">range];</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (current </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> delta </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> total </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) range </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">range, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;...&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">];</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">range, total];</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Navigation</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> nextPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">hasNextPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">c</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> c </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> prevPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">hasPrevPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">c</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> c </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> goToPage</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">page</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (page </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> &amp;&amp;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> page </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> totalPages</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    currentPage</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(page);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span></code></pre></div><h2 id="🔧-advanced-signal-features" tabindex="-1">🔧 Advanced Signal Features <a class="header-anchor" href="#🔧-advanced-signal-features" aria-label="Permalink to &quot;🔧 Advanced Signal Features&quot;">​</a></h2><h3 id="signal-equality-comparison" tabindex="-1">Signal Equality Comparison <a class="header-anchor" href="#signal-equality-comparison" aria-label="Permalink to &quot;Signal Equality Comparison&quot;">​</a></h3><p>Signals use <code>Object.is</code> for change detection. Only notify subscribers when values are actually different:</p><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> count</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// These won&#39;t trigger updates:</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Same value</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">prev</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> prev); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Returns same value</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// These will trigger updates:</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Different value</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">prev</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> prev </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Still 0? Actually returns 0? Wait...</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Be careful with functional updates!</span></span></code></pre></div><h3 id="batch-updates" tabindex="-1">Batch Updates <a class="header-anchor" href="#batch-updates" aria-label="Permalink to &quot;Batch Updates&quot;">​</a></h3><p>Multiple signal updates are batched into a single microtask:</p><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> firstName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;John&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> lastName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Doe&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> fullName</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> \`\${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">firstName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">} \${</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">lastName</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">()</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}\`</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">$.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">effect</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Full name:&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">fullName</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Logs: &#39;Full name: John Doe&#39;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Multiple updates in same tick - only one effect run!</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">firstName</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Jane&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">lastName</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Smith&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Only logs once: &#39;Full name: Jane Smith&#39;</span></span></code></pre></div><h3 id="infinite-loop-protection" tabindex="-1">Infinite Loop Protection <a class="header-anchor" href="#infinite-loop-protection" aria-label="Permalink to &quot;Infinite Loop Protection&quot;">​</a></h3><p>SigPro includes protection against infinite reactive loops:</p><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> a</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> b</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// This would create a loop, but SigPro prevents it</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">$.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">effect</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  a</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">b</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Reading b</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  b</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">a</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Reading a - loop detected!</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Throws: &quot;SigPro: Infinite reactive loop detected.&quot;</span></span></code></pre></div><h2 id="📊-performance-characteristics" tabindex="-1">📊 Performance Characteristics <a class="header-anchor" href="#📊-performance-characteristics" aria-label="Permalink to &quot;📊 Performance Characteristics&quot;">​</a></h2><table tabindex="0"><thead><tr><th>Operation</th><th>Complexity</th><th>Notes</th></tr></thead><tbody><tr><td>Signal read</td><td>O(1)</td><td>Direct value access</td></tr><tr><td>Signal write</td><td>O(n)</td><td>n = number of subscribers</td></tr><tr><td>Computed read</td><td>O(1) or O(m)</td><td>m = computation complexity</td></tr><tr><td>Effect run</td><td>O(s)</td><td>s = number of signal reads</td></tr></tbody></table><h2 id="🎯-best-practices" tabindex="-1">🎯 Best Practices <a class="header-anchor" href="#🎯-best-practices" aria-label="Permalink to &quot;🎯 Best Practices&quot;">​</a></h2><h3 id="_1-keep-signals-focused" tabindex="-1">1. Keep Signals Focused <a class="header-anchor" href="#_1-keep-signals-focused" aria-label="Permalink to &quot;1. Keep Signals Focused&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ❌ Avoid large monolithic signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> state</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  user: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">null</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  posts: [],</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  theme: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;light&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  notifications: []</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ✅ Split into focused signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">null</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> posts</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([]);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> theme</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;light&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> notifications</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([]);</span></span></code></pre></div><h3 id="_2-use-computed-for-derived-state" tabindex="-1">2. Use Computed for Derived State <a class="header-anchor" href="#_2-use-computed-for-derived-state" aria-label="Permalink to &quot;2. Use Computed for Derived State&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ❌ Don&#39;t compute in templates/effects</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">$.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">effect</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> items</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i.price, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  updateUI</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(total);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ✅ Compute with signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> items</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">i</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> i.price, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">));</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">$.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">effect</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> updateUI</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">total</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()));</span></span></code></pre></div><h3 id="_3-immutable-updates" tabindex="-1">3. Immutable Updates <a class="header-anchor" href="#_3-immutable-updates" aria-label="Permalink to &quot;3. Immutable Updates&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ❌ Don&#39;t mutate objects/arrays</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> user</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;John&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> });</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().name </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Jane&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Won&#39;t trigger updates!</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ✅ Create new objects/arrays</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">user</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(), name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Jane&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> });</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ❌ Don&#39;t mutate arrays</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> todos</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;a&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;b&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">push</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Won&#39;t trigger updates!</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ✅ Create new arrays</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(), </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;c&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span></code></pre></div><h3 id="_4-functional-updates-for-dependencies" tabindex="-1">4. Functional Updates for Dependencies <a class="header-anchor" href="#_4-functional-updates-for-dependencies" aria-label="Permalink to &quot;4. Functional Updates for Dependencies&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ❌ Avoid if new value depends on current</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// ✅ Use functional update</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">prev</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> prev </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span></code></pre></div><h3 id="_5-clean-up-effects" tabindex="-1">5. Clean Up Effects <a class="header-anchor" href="#_5-clean-up-effects" aria-label="Permalink to &quot;5. Clean Up Effects&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> userId</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Effects auto-clean in pages, but you can stop manually</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> stop</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> $.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">effect</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  fetchUser</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">userId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Later, if needed</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">stop</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span></code></pre></div><h2 id="🚀-real-world-examples" tabindex="-1">🚀 Real-World Examples <a class="header-anchor" href="#🚀-real-world-examples" aria-label="Permalink to &quot;🚀 Real-World Examples&quot;">​</a></h2><h3 id="form-state-management" tabindex="-1">Form State Management <a class="header-anchor" href="#form-state-management" aria-label="Permalink to &quot;Form State Management&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Form state</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> formData</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  username: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  email: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  age: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  newsletter: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Touched fields (for validation UI)</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> touched</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  username: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  email: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  age: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Validation rules</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> validations</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  username</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">value</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    value.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> &gt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 3</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ?</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> null</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Username must be at least 3 characters&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  email</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">value</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">    /</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#032F62;--shiki-dark:#DBEDFF;">@</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#22863A;--shiki-light-font-weight:bold;--shiki-dark:#85E89D;--shiki-dark-font-weight:bold;">\\.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">[</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">^</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">\\s@]</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+$</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">/</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">test</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(value) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">?</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> null</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Invalid email&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  age</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">value</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    !</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">value </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">||</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (value </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 18</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> &amp;&amp;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> value </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 120</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">?</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> null</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;Age must be 18-120&#39;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Validation signals</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> errors</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> data</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> result</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {};</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  Object.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">keys</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(validations).</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">field</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> error</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> validations[field](data[field]);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (error) result[field] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> error;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isValid</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> Object.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">keys</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">errors</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()).</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ===</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Field helpers</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> fieldProps</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">field</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ({</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  value: </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()[field],</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  error: </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">touched</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()[field] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">?</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> errors</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()[field] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">:</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> null</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">,</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  onChange</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">e</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> value</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e.target.type </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;checkbox&#39;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ?</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e.target.checked </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">:</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> e.target.value;</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      [field]: value</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  },</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  onBlur</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">: () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    touched</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">touched</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      [field]: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">true</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Form submission</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> submitAttempts</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isSubmitting</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> handleSubmit</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> async</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  submitAttempts</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">s</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> s </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">isValid</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) {</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">    // Mark all fields as touched to show errors</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    touched</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(Object.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">keys</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()).</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">acc</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">field</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">acc,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      [field]: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">true</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    }), {}));</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  isSubmitting</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">true</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  try</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    await</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> saveForm</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">    // Reset form on success</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    formData</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ username: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, email: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, age: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, newsletter: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> });</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    touched</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({ username: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, email: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, age: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">finally</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    isSubmitting</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span></code></pre></div><h3 id="todo-app-with-filters" tabindex="-1">Todo App with Filters <a class="header-anchor" href="#todo-app-with-filters" aria-label="Permalink to &quot;Todo App with Filters&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// State</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> todos</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, text: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Learn SigPro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, completed: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">true</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, text: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Build an app&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, completed: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, text: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Write docs&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, completed: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> filter</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;all&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// &#39;all&#39;, &#39;active&#39;, &#39;completed&#39;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> newTodoText</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Computed values</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> filteredTodos</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> all</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  switch</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    case</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;active&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> all.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">t</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> !</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">t.completed);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    case</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;completed&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> all.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">t</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> t.completed);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    default</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">:</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> all;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> activeCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">t</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> !</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">t.completed).</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> completedCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">t</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> t.completed).</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> hasCompleted</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> completedCount</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Actions</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> addTodo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> text</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> newTodoText</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">trim</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (text) {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        id: Date.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">now</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        text,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        completed: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">false</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    ]);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    newTodoText</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> toggleTodo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">id</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">todo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    todo.id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> id </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ?</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">todo, completed: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">todo.completed }</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      :</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> todo</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  ));</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> deleteTodo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">id</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">todo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> todo.id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!==</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> id));</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> clearCompleted</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">filter</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">todo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> !</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">todo.completed));</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> toggleAll</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> allCompleted</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> activeCount</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">todos</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">todo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> ({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    ...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">todo,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    completed: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">allCompleted</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  })));</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span></code></pre></div><h3 id="shopping-cart" tabindex="-1">Shopping Cart <a class="header-anchor" href="#shopping-cart" aria-label="Permalink to &quot;Shopping Cart&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Products catalog</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> products</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">([</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Laptop&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">999</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, stock: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Mouse&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">29</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, stock: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">20</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Keyboard&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">79</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, stock: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> },</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  { id: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">4</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, name: </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;Monitor&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, price: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">299</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, stock: </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Cart state</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> cart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({});</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> selectedProduct</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">null</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> quantity</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Computed cart values</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> cartItems</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> items</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> [];</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  Object.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">entries</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()).</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(([</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">productId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">qty</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">]) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> product</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> products</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">find</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">p</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> p.id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> parseInt</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(productId));</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (product) {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      items.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">push</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">        ...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">product,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        quantity: qty,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        subtotal: product.price </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> qty</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  });</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> items;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> itemCount</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  cartItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.quantity, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> subtotal</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  cartItems</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">reduce</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">sum</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">item</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> sum </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> item.subtotal, </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">)</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> tax</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0.10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> shipping</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 100</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ?</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> :</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 10</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> total</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> subtotal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> tax</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> shipping</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> isCartEmpty</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> itemCount</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Cart actions</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> addToCart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">product</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">qty</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> currentQty</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()[product.id] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">||</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> newQty</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> currentQty </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">+</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> qty;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (newQty </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> product.stock) {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">    cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      [product.id]: newQty</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    });</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    return</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> true</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> false</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> updateQuantity</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">productId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">newQty</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> product</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> products</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">find</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">p</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> p.id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> productId);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (newQty </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> product.stock) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (newQty </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&lt;=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">      removeFromCart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(productId);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">else</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">      cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">        ...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(),</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        [productId]: newQty</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  }</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> removeFromCart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">productId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> newCart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() };</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  delete</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> newCart[productId];</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">  cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(newCart);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> clearCart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">({});</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Stock management</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> productStock</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">productId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> product</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> products</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">().</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">find</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">p</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> p.id </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">===</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> productId);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">product) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">return</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> inCart</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> cart</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()[productId] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">||</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> product.stock </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">-</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> inCart;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> isInStock</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">productId</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">qty</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> productStock</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(productId) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">&gt;=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> qty;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span></code></pre></div><h2 id="📈-debugging-signals" tabindex="-1">📈 Debugging Signals <a class="header-anchor" href="#📈-debugging-signals" aria-label="Permalink to &quot;📈 Debugging Signals&quot;">​</a></h2><h3 id="logging-signal-changes" tabindex="-1">Logging Signal Changes <a class="header-anchor" href="#logging-signal-changes" aria-label="Permalink to &quot;Logging Signal Changes&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Wrap a signal to log changes</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> withLogging</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">args</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (args.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> oldValue</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> result</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">args);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">\`\${</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">name</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">}:\`</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, oldValue, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;-&gt;&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> result;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    }</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    return</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Usage</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> count</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> withLogging</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">$</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">), </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;count&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">5</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">); </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Logs: &quot;count: 0 -&gt; 5&quot;</span></span></code></pre></div><h3 id="signal-inspector" tabindex="-1">Signal Inspector <a class="header-anchor" href="#signal-inspector" aria-label="Permalink to &quot;Signal Inspector&quot;">​</a></h3><div class="language-javascript vp-adaptive-theme"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki shiki-themes github-light github-dark vp-code" tabindex="0"><code><span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">import</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { $ } </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">from</span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;"> &#39;sigpro&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Create an inspectable signal</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> createInspector</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> signals</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> new</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> Map</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> createSignal</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">initialValue</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">name</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> signal</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> $</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(initialValue);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    signals.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">set</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(signal, { name, subscribers: </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">new</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> Set</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() });</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    </span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">    // Wrap to track subscribers</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> wrapped</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">args</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      if</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> (</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">!</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">args.</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">length</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> &amp;&amp;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> activeEffect) {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">        const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> info</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> signals.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">get</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(wrapped);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        info.subscribers.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">add</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(activeEffect);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      }</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">      return</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">...</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">args);</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> wrapped;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  const</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> getInfo</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> () </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> info</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {};</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    signals.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">forEach</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">((</span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">data</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">) </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      info[data.name] </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        subscribers: data.subscribers.size,</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">        value: </span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">signal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">()</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">      };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">    });</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">    return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> info;</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">  </span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">  return</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> { createSignal, getInfo };</span></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">};</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// Usage</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> inspector</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> createInspector</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">();</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> count</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> inspector.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">createSignal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">0</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;count&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">const</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> doubled</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> =</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> inspector.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">createSignal</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=&gt;</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> count</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">() </span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">*</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;"> 2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">, </span><span style="--shiki-light:#032F62;--shiki-dark:#9ECBFF;">&#39;doubled&#39;</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">);</span></span>
<span class="line"></span>
<span class="line"><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">console.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">log</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">(inspector.</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;">getInfo</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">());</span></span>
<span class="line"><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;">// { count: { subscribers: 0, value: 0 }, doubled: { subscribers: 0, value: 0 } }</span></span></code></pre></div><h2 id="📊-summary" tabindex="-1">📊 Summary <a class="header-anchor" href="#📊-summary" aria-label="Permalink to &quot;📊 Summary&quot;">​</a></h2><table tabindex="0"><thead><tr><th>Feature</th><th>Description</th></tr></thead><tbody><tr><td><strong>Basic Signals</strong></td><td>Hold values and notify on change</td></tr><tr><td><strong>Computed Signals</strong></td><td>Auto-updating derived values</td></tr><tr><td><strong>Automatic Tracking</strong></td><td>Dependencies tracked automatically</td></tr><tr><td><strong>Batch Updates</strong></td><td>Multiple updates batched in microtask</td></tr><tr><td><strong>Infinite Loop Protection</strong></td><td>Prevents reactive cycles</td></tr><tr><td><strong>Zero Dependencies</strong></td><td>Pure vanilla JavaScript</td></tr></tbody></table><hr><blockquote><p><strong>Pro Tip:</strong> Signals are the foundation of reactivity in SigPro. Master them, and you&#39;ve mastered 80% of the library!</p></blockquote>`,82)])])}const y=i(k,[["render",l]]);export{g as __pageData,y as default};