🛑 Untracking: $.ignore( )

The $.ignore function allows you to read a signal's value inside an effect or a computed signal without creating a dependency.

🛠 Function Signature

$.ignore(callback: Function): any

Parameter	Type	Required	Description
callback	Function	Yes	A function where signals can be read "silently".

Returns: Whatever the callback function returns.

---

📖 Usage Patterns

1. Preventing Dependency Tracking

Normally, reading a signal inside $.effect makes the effect re-run when that signal changes. $.ignore breaks this link.

const count = $(0);
const logLabel = $("System Log");

$.effect(() => {
  // This effect tracks 'count'...
  const currentCount = count();
  
  // ...but NOT 'logLabel'. 
  // Changing 'logLabel' will NOT re-run this effect.
  const label = $.ignore(() => logLabel());
  
  console.log(`${label}: ${currentCount}`);
});

count(1);     // Console: "System Log: 1" (Triggers re-run)
logLabel("UI"); // Nothing happens in console (Ignored)

2. Reading State in Event Handlers

Inside complex UI logic, you might want to take a "snapshot" of a signal without triggering a reactive chain.

const handleClick = () => {
  // Accessing state without letting the caller know we touched it
  const data = $.ignore(() => mySignal());
  process(data);
};

3. Avoiding Infinite Loops

If you need to write to a signal based on its own value inside an effect (and you aren't using the functional updater), $.ignore prevents the effect from triggering itself.

$.effect(() => {
  const value = someSignal();
  
  if (value > 100) {
    // We update the signal, but we ignore the read to avoid a loop
    $.ignore(() => someSignal(0));
  }
});

---

💡 Why use it?

• Performance: Prevents expensive effects from running when non-essential data changes.
• Logic Control: Allows "sampling" a signal at a specific point in time.
• Safety: Essential for complex state orchestrations where circular dependencies might occur.