createNotifier

Features

createNotifier provides a way to manually trigger signal re-computations by referencing the created notifier signal. It can also automatically react to changes in other signals through dependency tracking.

Common Use Cases

• Manually triggering a “refresh” and reacting to it
• Mutating a Map and having a way to react to that map changing
• Triggering a re-computation on some kind of event/life cycle hook
• Combining manual notifications with automatic dependency tracking

Basic Usage

Create a simple notifier:

import { createNotifier } from 'ngxtension/create-notifier';
refreshNotifier = createNotifier();

Trigger the signal update:

refreshNotifier.notify();

React to notifications in computed or effect:

effect(() => {
  refreshNotifier.listen();

  // whatever code you want to run whenever
  // refreshNotifier.notify() is called
});

Avoiding Initial Effect Execution

An effect runs once initially before notify() is explicitly called. Since the internal counter begins at 0, you can skip the initial run:

effect(() => {
  if (refreshNotifier.listen()) {
    // Will NOT run on init
    // whatever code you want to run whenever
    // refreshNotifier.notify() is called
  }
});

The if condition initially fails because refreshNotifier.listen() returns 0, but passes once notify() has been called.

Dependency Tracking

You can configure a notifier to automatically increment whenever specified signals change. This combines manual notifications with reactive dependency tracking.

Basic Dependency Tracking

userId = signal(1);

userNotifier = createNotifier({ deps: [userId] });

Now userNotifier.listen() will increment both when notify() is called and when userId changes:

effect(() => {
  console.log('User notifier changed:', userNotifier.listen());
  // Runs when userId changes OR when notify() is called
});

// Both of these will trigger the effect:
userId.set(2); // Triggers via dependency
userNotifier.notify(); // Triggers manually

Multiple Dependencies

Track multiple signals simultaneously:

userId = signal(1);
tenantId = signal('tenant-a');

compositeNotifier = createNotifier({
  deps: [userId, tenantId],
});

The notifier increments whenever any of the dependencies change.

Controlling Initial Emission

By default, notifiers with dependencies start at 1 (emitting immediately). Control this with depsEmitInitially:

// Emit immediately (default behavior)
notifier = createNotifier({
  deps: [someSignal],
  depsEmitInitially: true, // starts at 1 (default)
});

// Don't emit initially
notifier = createNotifier({
  deps: [someSignal],
  depsEmitInitially: false, // starts at 0
});

When depsEmitInitially: false, the notifier starts at 0 like a dependency-free notifier, even though it tracks signals. The first increment happens only when dependencies change or notify() is called.