---
category: Watch
alias: ignorableWatch
---

# watchIgnorable

Ignorable watch

## Usage

Extended `watch` that returns extra `ignoreUpdates(updater)` and `ignorePrevAsyncUpdates()` to ignore particular updates to the source.

```ts
import { watchIgnorable } from '@vueuse/core';
import { nextTick, shallowRef } from 'vue';

const source = shallowRef('foo');

const { stop, ignoreUpdates } = watchIgnorable(source, (v) => console.log(`Changed to ${v}!`));

source.value = 'bar';
await nextTick(); // logs: Changed to bar!

ignoreUpdates(() => {
  source.value = 'foobar';
});
await nextTick(); // (nothing happened)

source.value = 'hello';
await nextTick(); // logs: Changed to hello!

ignoreUpdates(() => {
  source.value = 'ignored';
});
source.value = 'logged';

await nextTick(); // logs: Changed to logged!
```

## WatchOptionFlush timing

`watchIgnorable` accepts the same options as `watch` and uses the same defaults.
So, by default the composable works using `flush: 'pre'`.

## `ignorePrevAsyncUpdates`

This feature is only for async flush `'pre'` and `'post'`. If `flush: 'sync'` is used, `ignorePrevAsyncUpdates()` is a no-op as the watch will trigger immediately after each update to the source. It is still provided for sync flush so the code can be more generic.

```ts
import { watchIgnorable } from '@vueuse/core';
import { nextTick, shallowRef } from 'vue';

const source = shallowRef('foo');

const { ignorePrevAsyncUpdates } = watchIgnorable(source, (v) => console.log(`Changed to ${v}!`));

source.value = 'bar';
await nextTick(); // logs: Changed to bar!

source.value = 'good';
source.value = 'by';
ignorePrevAsyncUpdates();

await nextTick(); // (nothing happened)

source.value = 'prev';
ignorePrevAsyncUpdates();
source.value = 'after';

await nextTick(); // logs: Changed to after!
```

## Recommended Readings

- [Ignorable Watch](https://patak.dev/vue/ignorable-watch.html) - by [@patak-dev](https://github.com/patak-dev)

## Type Declarations

```ts
export type IgnoredUpdater = (updater: () => void) => void;
export type IgnoredPrevAsyncUpdates = () => void;
export interface WatchIgnorableReturn {
  ignoreUpdates: IgnoredUpdater;
  ignorePrevAsyncUpdates: IgnoredPrevAsyncUpdates;
  stop: WatchStopHandle;
}
export declare function watchIgnorable<
  T extends Readonly<MultiWatchSources>,
  Immediate extends Readonly<boolean> = false,
>(
  sources: [...T],
  cb: WatchCallback<MapSources<T>, MapOldSources<T, Immediate>>,
  options?: WatchWithFilterOptions<Immediate>,
): WatchIgnorableReturn;
export declare function watchIgnorable<T, Immediate extends Readonly<boolean> = false>(
  source: WatchSource<T>,
  cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
  options?: WatchWithFilterOptions<Immediate>,
): WatchIgnorableReturn;
export declare function watchIgnorable<
  T extends object,
  Immediate extends Readonly<boolean> = false,
>(
  source: T,
  cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
  options?: WatchWithFilterOptions<Immediate>,
): WatchIgnorableReturn;
/** @deprecated use `watchIgnorable` instead */
export declare const ignorableWatch: typeof watchIgnorable;
```
