1---
2category: Utilities
3related: useThrottleFn
4---
5 
6# useDebounceFn
7 
8Debounce execution of a function.
9 
10> 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.
11 
12## Usage
13 
14```ts
15import { useDebounceFn, useEventListener } from '@vueuse/core'
16 
17const debouncedFn = useDebounceFn(() => {
18  // do something
19}, 1000)
20 
21useEventListener(window, 'resize', debouncedFn)
22```
23 
24You can also pass a 3rd parameter to this, with a maximum wait time, similar to [lodash debounce](https://lodash.com/docs/4.17.15#debounce)
25 
26```ts
27import { useDebounceFn, useEventListener } from '@vueuse/core'
28 
29// If no invokation after 5000ms due to repeated input,
30// the function will be called anyway.
31const debouncedFn = useDebounceFn(() => {
32  // do something
33}, 1000, { maxWait: 5000 })
34 
35useEventListener(window, 'resize', debouncedFn)
36```
37 
38Optionally, you can get the return value of the function using promise operations.
39 
40```ts
41import { useDebounceFn } from '@vueuse/core'
42 
43const debouncedRequest = useDebounceFn(() => 'response', 1000)
44 
45debouncedRequest().then((value) => {
46  console.log(value) // 'response'
47})
48 
49// or use async/await
50async function doRequest() {
51  const value = await debouncedRequest()
52  console.log(value) // 'response'
53}
54```
55 
56Since 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.
57 
58```ts
59import { useDebounceFn } from '@vueuse/core'
60 
61const debouncedRequest = useDebounceFn(() => 'response', 1000, { rejectOnCancel: true })
62 
63debouncedRequest()
64  .then((value) => {
65    // do something
66  })
67  .catch(() => {
68    // do something when canceled
69  })
70 
71// calling it again will cancel the previous request and gets rejected
72setTimeout(debouncedRequest, 500)
73```
74 
75## Recommended Reading
76 
77- [**Debounce vs Throttle**: Definitive Visual Guide](https://kettanaito.com/blog/debounce-vs-throttle)
78 
79## Type Declarations
80 
81```ts
82export type UseDebounceFnReturn<T extends FunctionArgs> = PromisifyFn<T>
83/**
84 * Debounce execution of a function.
85 *
86 * @see https://vueuse.org/useDebounceFn
87 * @param  fn          A function to be executed after delay milliseconds debounced.
88 * @param  ms          A zero-or-greater delay in milliseconds. For event callbacks, values around 100 or 250 (or even higher) are most useful.
89 * @param  options     Options
90 *
91 * @return A new, debounce, function.
92 *
93 * @__NO_SIDE_EFFECTS__
94 */
95export declare function useDebounceFn<T extends FunctionArgs>(
96  fn: T,
97  ms?: MaybeRefOrGetter<number>,
98  options?: DebounceFilterOptions,
99): UseDebounceFnReturn<T>
100```
101