watchThrottled
Throttled watch. The callback will be invoked at most once per specified duration.
Demo
Delay is set to 1000ms for this demo.
Input:
Times Updated: 0
Usage
Similar to watch, but offering extra options throttle, trailing, and leading which will be applied to the callback function.
ts
import { watchThrottled } from '@vueuse/core'
watchThrottled(
source,
() => { console.log('changed!') },
{ throttle: 500 },
)Options
| Option | Type | Default | Description |
|---|---|---|---|
throttle | MaybeRefOrGetter<number> | 0 | Throttle interval in ms (can be reactive) |
trailing | boolean | true | Invoke on the trailing edge |
leading | boolean | true | Invoke on the leading edge |
All standard watch options (deep, immediate, flush, etc.) are also supported.
Leading and Trailing
Control when the callback is invoked:
ts
import { watchThrottled } from '@vueuse/core'
// Only invoke at the start of each throttle period
watchThrottled(source, callback, {
throttle: 500,
leading: true,
trailing: false,
})
// Only invoke at the end of each throttle period
watchThrottled(source, callback, {
throttle: 500,
leading: false,
trailing: true,
})How It Works
It's essentially a shorthand for the following code:
ts
import { throttleFilter, watchWithFilter } from '@vueuse/core'
watchWithFilter(
source,
() => { console.log('changed!') },
{
eventFilter: throttleFilter(500),
},
)Type Declarations
Show Type Declarations
ts
export interface WatchThrottledOptions<
Immediate,
> extends WatchOptions<Immediate> {
throttle?: MaybeRefOrGetter<number>
trailing?: boolean
leading?: boolean
}
export declare function watchThrottled<
T,
Immediate extends Readonly<boolean> = false,
>(
source: WatchSource<T>,
cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
options?: WatchThrottledOptions<Immediate>,
): WatchHandle
export declare function watchThrottled<
T extends Readonly<MultiWatchSources>,
Immediate extends Readonly<boolean> = false,
>(
sources: [...T],
cb: WatchCallback<MapSources<T>, MapOldSources<T, Immediate>>,
options?: WatchThrottledOptions<Immediate>,
): WatchHandle
export declare function watchThrottled<
T extends object,
Immediate extends Readonly<boolean> = false,
>(
source: T,
cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
options?: WatchThrottledOptions<Immediate>,
): WatchHandle
/** @deprecated use `watchThrottled` instead */
export declare const throttledWatch: typeof watchThrottledSource
Contributors
Anthony Fu
Anthony Fu
Vida Xie
sun0day
山吹色御守
Kricsleo
Arthur Darkstone
IlyaL
OrbisK
丶远方
lvjiaxuan
Joe Zimmerman
webfansplz