/vueuse-functions

useDebounceFn

Debounce execution of a function.

Debounce is an overloaded waiter: if you keep asking, your requests will be ignored until you stop and give them some time to think about your latest inquiry.

Usage

import { useDebounceFn, useEventListener } from '@vueuse/core'

const debouncedFn = useDebounceFn(() => {
  // do something
}, 1000)

useEventListener(window, 'resize', debouncedFn)

You can also pass a 3rd parameter to this, with a maximum wait time, similar to lodash debounce

import { useDebounceFn, useEventListener } from '@vueuse/core'

// If no invokation after 5000ms due to repeated input,
// the function will be called anyway.
const debouncedFn = useDebounceFn(() => {
  // do something
}, 1000, { maxWait: 5000 })

useEventListener(window, 'resize', debouncedFn)

Optionally, you can get the return value of the function using promise operations.

import { useDebounceFn } from '@vueuse/core'

const debouncedRequest = useDebounceFn(() => 'response', 1000)

debouncedRequest().then((value) => {
  console.log(value) // 'response'
})

// or use async/await
async function doRequest() {
  const value = await debouncedRequest()
  console.log(value) // 'response'
}

Since unhandled rejection error is quite annoying when developer doesn't need the return value, the promise will NOT be rejected if the function is canceled by default. You need to specify the option rejectOnCancel: true to capture the rejection.

import { useDebounceFn } from '@vueuse/core'

const debouncedRequest = useDebounceFn(() => 'response', 1000, { rejectOnCancel: true })

debouncedRequest()
  .then((value) => {
    // do something
  })
  .catch(() => {
    // do something when canceled
  })

// calling it again will cancel the previous request and gets rejected
setTimeout(debouncedRequest, 500)

Recommended Reading

• Debounce vs Throttle: Definitive Visual Guide

Type Declarations

export type UseDebounceFnReturn<T extends FunctionArgs> = PromisifyFn<T>
/**
 * Debounce execution of a function.
 *
 * @see https://vueuse.org/useDebounceFn
 * @param  fn          A function to be executed after delay milliseconds debounced.
 * @param  ms          A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
 * @param  options     Options
 *
 * @return A new, debounce, function.
 *
 * @__NO_SIDE_EFFECTS__
 */
export declare function useDebounceFn<T extends FunctionArgs>(
  fn: T,
  ms?: MaybeRefOrGetter<number>,
  options?: DebounceFilterOptions,
): UseDebounceFnReturn<T>