watchOnce

v0.0.15testeddemo

Shorthand for `watch` that automatically stops after the callback fires once.

Examples

const count = ref(0);
watchOnce(count, value => console.log('fired once with', value));

watchOnce([a, b], ([a, b]) => console.log(a, b));

Demo

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Signatures

export function watchOnce<T>(
  source: WatchSource<T>,
  cb: WatchCallback<T, T | undefined>,
  options?: WatchOnceOptions<true>,
): WatchHandle;

export function watchOnce<T extends Readonly<MultiWatchSources>>(
  source: [...T],
  cb: WatchCallback<MapSources<T>, MapOldSources<T, true>>,
  options?: WatchOnceOptions<true>,
): WatchHandle;

export function watchOnce<T extends object>(
  source: T,
  cb: WatchCallback<T, T | undefined>,
  options?: WatchOnceOptions<true>,
): WatchHandle;

Parameters

Parameter	Type	Default	Description
`source`	`object \| WatchSource<unknown> \| MultiWatchSources`	—	The reactive source (ref, getter, reactive object, or array of sources) to watch
`cb`	`WatchCallback`	—	Invoked once with the new value, old value, and `onCleanup`
`options`?	`WatchOnceOptions<boolean> \| undefined`	—	Watch options (`immediate`, `deep`, `flush`); `once` is forced on

Returns

WatchHandleA handle to stop watching before the first trigger