# ⚡ SigPro – Complete API Reference

SigPro is a **Real‑DOM first** reactive micro‑framework. No virtual DOM, no diffing overhead – it updates the DOM directly with surgical precision. Built‑in automatic cleanup prevents memory leaks, and the API is designed to be both tiny and powerful.

```javascript
import { $, $$, watch, h, when, each, fx, router, req, mount, batch } from 'sigpro'
// Or, if you prefer the global style in an ESM environment:
// import { sigpro } from 'sigpro'; sigpro();   // then $, h, div... become window globals
// In a classic IIFE script (<script src="sigpro.js">), everything is available globally automatically.
```

---

## 🔁 Core Reactivity

### `$(value, localStorageKey?)` – Signal & Computed

Creates a reactive signal. If a function is passed, it becomes a **computed** signal that caches its result until dependencies change.

| Usage | Description |
|-------|-------------|
| `const count = $(0)` | Basic signal, returns a getter/setter: `count()` reads, `count(5)` writes. |
| `const double = $( () => count() * 2 )` | Computed signal – updates automatically when `count` changes. |
| `const stored = $('hello', 'myKey')` | Persisted signal – reads/writes to `localStorage`. |

**Example**  
```javascript
const count = $(0)
const double = $( () => count() * 2 )

watch(() => {
  console.log(`count = ${count()}, double = ${double()}`)
}) // logs on every change

count(5) // triggers log: count=5, double=10
```

---

### `$$(object)` – Deep Reactive Proxy

Makes a plain object (and all nested objects) deeply reactive. Any property access is tracked, any mutation triggers updates.

```javascript
const state = $$({ user: { name: 'Alice', age: 30 }, items: [1,2,3] })

watch(() => {
  console.log(state.user.name) // tracks `user.name`
})

state.user.name = 'Bob' // triggers the effect
```

> **Note**: `$$` caches proxies per original object, so calling `$$` multiple times on the same object returns the same proxy.

---

### `watch(source, callback?)` – Reactive Effect

Two modes:

1. **Auto‑track mode** – pass a function: `watch(() => { /* reads signals */ })`  
   Automatically re‑runs whenever any signal read inside changes.

2. **Explicit mode** – pass an array of signals and a callback:  
   `watch([count, double], () => { ... })`  
   Runs the callback when any of the listed signals change. The callback receives the new values.

Both modes return a `stop` function that disposes the effect.

```javascript
// auto mode
const stop = watch(() => console.log(count()))

// explicit mode
watch([count, double], ([newCount, newDouble]) => {
  console.log(newCount, newDouble)
})
```

> **Important**: Effects are depth‑aware – they run in topological order, parents before children.

---

## 🧱 Components & DOM (Hyperscript)

### `h(tag, props, children)` – Create DOM Nodes

The universal builder. `props` can be omitted. Children can be strings, numbers, nodes, arrays, or **dynamic functions**.

| Feature | Example |
|---------|---------|
| Standard attributes | `h('div', { class: 'box', id: 'main' })` |
| Events | `onClick: (e) => ...` (automatically cleaned up) |
| Reactive attributes | `class: () => count() > 0 ? 'positive' : 'negative'` |
| Two‑way binding | `value: mySignal` (works on `input`, `textarea`, `select`) |
| Refs | `ref: (el) => ...` or `ref: { current: null }` |
| SVG support | tag names like `svg`, `circle`, `path` – sets correct namespace |
| Dangerous URL sanitising | `href` / `src` with `javascript:` or `data:` are blocked → `'#'` |

**Dynamic children** – pass a function as a child, it will be re‑executed and the DOM patched automatically:

```javascript
h('div', {}, [
  () => count() > 0 ? h('span', {}, 'positive') : h('span', {}, 'zero or negative')
])
```

### Tag shortcuts

When using the **ESM module with named imports**, you can import the tag helpers individually:

```javascript
import { div, h1, button } from 'sigpro'

div({ class: 'container' }, [
  h1({}, 'Title'),
  button({ onClick: () => alert('hi') }, 'Click me')
])
```

If you prefer the **global style** (all tags and core functions on `window`), either:
- Use the classic IIFE script: `<script src="sigpro.js"></script>`
- Or in ESM, call `sigpro()` after importing: `import { sigpro } from 'sigpro'; sigpro();`

After that, you can write `div()`, `span()`, etc. directly, without any import.

Available tags: `a`, `abbr`, `article`, `aside`, `audio`, `b`, `blockquote`, `br`, `button`, `canvas`, `caption`, `cite`, `code`, `col`, `colgroup`, `datalist`, `dd`, `del`, `details`, `dfn`, `dialog`, `div`, `dl`, `dt`, `em`, `embed`, `fieldset`, `figcaption`, `figure`, `footer`, `form`, `h1`…`h6`, `header`, `hr`, `i`, `iframe`, `img`, `input`, `ins`, `kbd`, `label`, `legend`, `li`, `main`, `mark`, `meter`, `nav`, `object`, `ol`, `optgroup`, `option`, `output`, `p`, `picture`, `pre`, `progress`, `section`, `select`, `slot`, `small`, `source`, `span`, `strong`, `sub`, `summary`, `sup`, `svg`, `table`, `tbody`, `td`, `template`, `textarea`, `tfoot`, `th`, `thead`, `time`, `tr`, `u`, `ul`, `video`.

---

## 🧩 Flow Control Components

### `when(condition, thenComponent, elseComponent?)`

Reactive conditional rendering. `condition` can be a boolean, a signal, or any function that returns a boolean. Both branches can be `Node`, `() => Node`, or `null`. Automatically disposes the unmounted branch.

```javascript
when(
  () => user.loggedIn(),
  () => div({}, 'Welcome back!'),
  () => button({ onClick: () => login() }, 'Login')
)
```

---

### `each(source, itemRenderer, keyFn)`

Optimised keyed list rendering. `source` can be an array or a signal/function returning an array. `itemRenderer(item, index)` returns a Node (or a function that returns Nodes). `keyFn(item, index)` returns a unique identifier – **required** for efficient DOM reuse.

```javascript
const items = $([{ id: 1, text: 'a' }, { id: 2, text: 'b' }])

each(items,
  (item) => Li({}, item.text),
  (item) => item.id
)
```

When the array changes, elements are added, removed, or reordered with minimal DOM operations.

---

## 💥 Batch

### `batch(fn)`

Batch multiple reactive updates into a single flush, improving performance.

```javascript
batch(() => {
  count(1)
  name('John')
  // effects run only once after the batch ends
})
```

---

## ✨ Animations – `fx(options, child)`

Applies smooth enter animations (CSS transitions / keyframes). Returns the modified element.

```javascript
fx({ name: 'fade', duration: 300 }, 
  div({}, 'Hello')
)
```

**Options**  
- `name` – uses predefined keyframes `${name}-in` (you must define them in your CSS)  
- `duration` – in ms (default 200)  
- `scale` – adds `scale(0.95)` → `none`  
- `slide` – adds `translateY(-10px)` → `none`  
- `rotate` – adds `rotate(-2deg)` → `none`  
- `blur` – adds `blur(4px)` → `none`

If `name` is given, it sets `animation: ${name}-in ${duration}ms`. Otherwise it applies a smooth transition from the initial transform/filter to the final state.

---

## 🧭 Router – `router(routes)`

Hash‑based SPA router. Returns a DOM node that renders the current route.

```javascript
const routes = [
  { path: '/', component: () => div({}, 'Home') },
  { path: '/user/:id', component: (params) => div({}, `User ${params.id}`) },
  { path: '*', component: () => div({}, '404') }
]

const App = () => div({}, [
  a({ href: '#/' }, 'Home'),
  a({ href: '#/user/42' }, 'User 42'),
  router(routes)
])
```

**API**

| Method | Description |
|--------|-------------|
| `router.params()` | Returns a reactive signal of current route params (e.g., `{ id: '42' }`). |
| `router.to(path)` | Navigate to a new hash (e.g., `router.to('/user/5')`). Prepend `#` automatically. |
| `router.back()` | Go back in history. |
| `router.path()` | Returns current hash path without `#` (e.g., `/user/42`). |

---

## 🌐 HTTP Requests – `req(config)`

Creates a reactive request controller with built‑in loading/error/data signals and abort support.

```javascript
const fetchUser = req({ url: '/api/user/1', method: 'GET' })

// start the request
fetchUser.run().catch(console.error)

// reactively display state
watch(() => {
  if (fetchUser.loading()) console.log('loading...')
  if (fetchUser.error()) console.error(fetchUser.error())
  if (fetchUser.data()) console.log(fetchUser.data())
})

// abort if needed
fetchUser.abort()
```

**Options**  
- `url` (required)  
- `method` (default `'GET'`)  
- `headers` (object, default `{}`)

**Return value**  
- `run(body?)` – initiates the request, returns a promise.  
- `abort()` – aborts the current request (AbortController).  
- `loading` – signal (boolean)  
- `error` – signal (`null` or error message)  
- `data` – signal (`null` or parsed JSON)

> **Note**: Automatically sets `Content-Type: application/json` unless `body` is a `FormData`. Timeout after 10 seconds aborts the request.

---

## 🚀 Mounting – `mount(component, target)`

Clears the target element and mounts the application. Returns the runtime instance (which has a `.destroy()` method).

```javascript
mount(() => App(), '#app')
// or
mount(App, document.body)
```

If you mount again on the same target, the previous instance is automatically destroyed.

---

## 🧹 Global Cleanup & Memory

SigPro tracks every effect, DOM event listener, and nested component. When a component is unmounted:
- All its effects are disposed.
- All DOM event listeners are removed.
- All `onUnmount` callbacks run.
- Child components are recursively destroyed.

You never need to manually clean up – just write reactive code.

---

## 📦 Full Example – Counter with Persistence

```javascript
import { $, watch, h, mount } from 'sigpro'

const count = $(0, 'counter') // persists in localStorage

const App = () =>
  div({ class: 'counter' }, [
    h1({}, () => `Count: ${count()}`),
    button({ onClick: () => count(count() + 1) }, '+'),
    button({ onClick: () => count(count() - 1) }, '-'),
    button({ onClick: () => count(0) }, 'Reset')
  ])

mount(App, '#app')
```

---

## 🔧 Customising the API (Renaming)

You can rename everything in one line:

```javascript
import { $ as signal, watch as effect, h as element, mount as render } from 'sigpro'
```

Or assign globally (after calling `sigpro()` or using the classic script):

```javascript
window.myReactive = $
```