/vueuse-functions

refThrottled

Throttle changing of a ref value.

Usage

import { refThrottled } from '@vueuse/core'
import { shallowRef } from 'vue'

const input = shallowRef('')
const throttled = refThrottled(input, 1000)

An example with object ref.

import { refThrottled } from '@vueuse/core'
import { shallowRef } from 'vue'

const data = shallowRef({
  count: 0,
  name: 'foo',
})
const throttled = refThrottled(data, 1000)

data.value = { count: 1, name: 'foo' }
console.log(throttled.value) // { count: 1, name: 'foo' } (immediate)

data.value = { count: 2, name: 'bar' }
data.value = { count: 3, name: 'baz' }
data.value = { count: 4, name: 'qux' }
console.log(throttled.value) // { count: 1, name: 'foo' } (still first value)

// After 1000ms, next change will be applied
await sleep(1100)
data.value = { count: 5, name: 'final' }
await nextTick()
console.log(throttled.value) // { count: 5, name: 'final' } (updated)

Trailing

If you don't want to watch trailing changes, set 3rd param false (it's true by default):

import { refThrottled } from '@vueuse/core'
import { shallowRef } from 'vue'

const input = shallowRef('')
const throttled = refThrottled(input, 1000, false)

Leading

Allows the callback to be invoked immediately (on the leading edge of the ms timeout). If you don't want this behavior, set the 4th param false (it's true by default):

import { refThrottled } from '@vueuse/core'
import { shallowRef } from 'vue'

const input = shallowRef('')
const throttled = refThrottled(input, 1000, undefined, false)

Recommended Reading

• Debounce vs Throttle: Definitive Visual Guide
• Debouncing and Throttling Explained Through Examples

Type Declarations

export type RefThrottledReturn<T = any> = Ref<T>
/**
 * Throttle execution of a function. Especially useful for rate limiting
 * execution of handlers on events like resize and scroll.
 *
 * @param value Ref value to be watched with throttle effect
 * @param  delay  A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
 * @param trailing if true, update the value again after the delay time is up
 * @param leading if true, update the value on the leading edge of the ms timeout
 */
export declare function refThrottled<T = any>(
  value: Ref<T>,
  delay?: number,
  trailing?: boolean,
  leading?: boolean,
): RefThrottledReturn<T>
/** @deprecated use `refThrottled` instead */
export declare const throttledRef: typeof refThrottled
/** @deprecated use `refThrottled` instead */
export declare const useThrottle: typeof refThrottled