Dependency

Track reactions by hand. A Dependency records which reactions are listening and re-fires them when you say so. Signals own one internally, which is how signal.depend(), signal.notify(), and signal.hasDependents() work.

Creating

Dependency

new Dependency(...metadata);

Creates a dependency tracker with an empty set of subscribers.

Parameters

Usage

import { Dependency } from '@semantic-ui/reactivity';

const dep = new Dependency();

Subscribing

depend

dependency.depend();

Records the currently running reaction as a subscriber. A no-op outside a reaction, so it is safe to call anywhere.

Usage

import { Dependency, reaction } from '@semantic-ui/reactivity';

const dep = new Dependency();

reaction(() => {
  dep.depend();
  // re-runs whenever dep.changed() fires
});

subscribers

dependency.subscribers;

The live Set of reactions currently subscribed. Read it to introspect, do not mutate it directly. Use remove to drop a subscriber.

Returns

A Set of subscribed reactions. Empty when nothing is listening.

Notifying

changed

dependency.changed(context);

Invalidates every subscribed reaction, scheduling them to re-run. Skips its bookkeeping entirely when nothing is listening.

Parameters

Usage

import { Dependency, reaction } from '@semantic-ui/reactivity';

const dep = new Dependency();

reaction(() => {
  dep.depend();
  console.log('ran');
});

dep.changed(); // logs 'ran' again

Removing

remove

dependency.remove(reaction);

Drops a single reaction from the subscriber set. The reaction stops re-running on future changed calls. Reactions are removed automatically when they stop, so you only need this for manual lifecycle control.

Parameters

Usage

import { Dependency, reaction } from '@semantic-ui/reactivity';

const dep = new Dependency();

const watcher = reaction(() => {
  dep.depend();
});

dep.remove(watcher); // watcher no longer fires on dep.changed()