ChatGPT解决这个技术问题 Extra ChatGPT

How to perform debounce?

How do you perform debounce in React.js?

I want to debounce the handleOnChange.

I tried with debounce(this.handleOnChange, 200) but it doesn't work.

function debounce(fn, delay) {
  var timer = null;
  return function() {
    var context = this,
      args = arguments;
    clearTimeout(timer);
    timer = setTimeout(function() {
      fn.apply(context, args);
    }, delay);
  };
}

var SearchBox = React.createClass({
  render: function() {
    return <input type="search" name="p" onChange={this.handleOnChange} />;
  },

  handleOnChange: function(event) {
    // make ajax call
  }
});
I met the same problem with you, superb answers below!but I think you used wrong way of debounce. here, when onChange={debounce(this.handleOnChange, 200)}/>, it will invoke debounce function every time. but ,in fact, what we need is invoke the function what debounce function returned.

S
Sebastien Lorber

2019: try hooks + promise debouncing

This is the most up to date version of how I would solve this problem. I would use:

awesome-debounce-promise to debounce the async function

use-constant to store that debounced function into the component

react-async-hook to get the result into my component

This is some initial wiring but you are composing primitive blocks on your own, and you can make your own custom hook so that you only need to do this once.

// Generic reusable hook
const useDebouncedSearch = (searchFunction) => {

  // Handle the input text state
  const [inputText, setInputText] = useState('');

  // Debounce the original search async function
  const debouncedSearchFunction = useConstant(() =>
    AwesomeDebouncePromise(searchFunction, 300)
  );

  // The async callback is run each time the text changes,
  // but as the search function is debounced, it does not
  // fire a new request on each keystroke
  const searchResults = useAsync(
    async () => {
      if (inputText.length === 0) {
        return [];
      } else {
        return debouncedSearchFunction(inputText);
      }
    },
    [debouncedSearchFunction, inputText]
  );

  // Return everything needed for the hook consumer
  return {
    inputText,
    setInputText,
    searchResults,
  };
};

And then you can use your hook:

const useSearchStarwarsHero = () => useDebouncedSearch(text => searchStarwarsHeroAsync(text))

const SearchStarwarsHeroExample = () => {
  const { inputText, setInputText, searchResults } = useSearchStarwarsHero();
  return (
    <div>
      <input value={inputText} onChange={e => setInputText(e.target.value)} />
      <div>
        {searchResults.loading && <div>...</div>}
        {searchResults.error && <div>Error: {search.error.message}</div>}
        {searchResults.result && (
          <div>
            <div>Results: {search.result.length}</div>
            <ul>
              {searchResults.result.map(hero => (
                <li key={hero.name}>{hero.name}</li>
              ))}
            </ul>
          </div>
        )}
      </div>
    </div>
  );
};

You will find this example running here and you should read react-async-hook documentation for more details.

2018: try promise debouncing

We often want to debounce API calls to avoid flooding the backend with useless requests.

In 2018, working with callbacks (Lodash/Underscore) feels bad and error-prone to me. It's easy to encounter boilerplate and concurrency issues due to API calls resolving in an arbitrary order.

I've created a little library with React in mind to solve your pains: awesome-debounce-promise.

This should not be more complicated than that:

const searchAPI = text => fetch('/search?text=' + encodeURIComponent(text));

const searchAPIDebounced = AwesomeDebouncePromise(searchAPI, 500);

class SearchInputAndResults extends React.Component {
  state = {
    text: '',
    results: null,
  };

  handleTextChange = async text => {
    this.setState({ text, results: null });
    const result = await searchAPIDebounced(text);
    this.setState({ result });
  };
}

The debounced function ensures that:

API calls will be debounced

the debounced function always returns a promise

only the last call's returned promise will resolve

a single this.setState({ result }); will happen per API call

Eventually, you may add another trick if your component unmounts:

componentWillUnmount() {
  this.setState = () => {};
}

Note that Observables (RxJS) can also be a great fit for debouncing inputs, but it's a more powerful abstraction which may be harder to learn/use correctly.

< 2017: still want to use callback debouncing?

The important part here is to create a single debounced (or throttled) function per component instance. You don't want to recreate the debounce (or throttle) function everytime, and you don't want either multiple instances to share the same debounced function.

I'm not defining a debouncing function in this answer as it's not really relevant, but this answer will work perfectly fine with _.debounce of underscore or lodash, as well as any user-provided debouncing function.

GOOD IDEA:

Because debounced functions are stateful, we have to create one debounced function per component instance.

ES6 (class property): recommended

class SearchBox extends React.Component {
    method = debounce(() => { 
      ...
    });
}

ES6 (class constructor)

class SearchBox extends React.Component {
    constructor(props) {
        super(props);
        this.method = debounce(this.method.bind(this),1000);
    }
    method() { ... }
}

ES5

var SearchBox = React.createClass({
    method: function() {...},
    componentWillMount: function() {
       this.method = debounce(this.method.bind(this),100);
    },
});

See JsFiddle: 3 instances are producing 1 log entry per instance (that makes 3 globally).

NOT a good idea:

var SearchBox = React.createClass({
  method: function() {...},
  debouncedMethod: debounce(this.method, 100);
});

It won't work, because during class description object creation, this is not the object created itself. this.method does not return what you expect because the this context is not the object itself (which actually does not really exist yet BTW as it is just being created).

NOT a good idea:

var SearchBox = React.createClass({
  method: function() {...},
  debouncedMethod: function() {
      var debounced = debounce(this.method,100);
      debounced();
  },
});

This time you are effectively creating a debounced function that calls your this.method. The problem is that you are recreating it on every debouncedMethod call, so the newly created debounce function does not know anything about former calls! You must reuse the same debounced function over time or the debouncing will not happen.

NOT a good idea:

var SearchBox = React.createClass({
  debouncedMethod: debounce(function () {...},100),
});

This is a little bit tricky here.

All the mounted instances of the class will share the same debounced function, and most often this is not what you want!. See JsFiddle: 3 instances are producting only 1 log entry globally.

You have to create a debounced function for each component instance, and not a single debounced function at the class level, shared by each component instance.

Take care of React's event pooling

This is related because we often want to debounce or throttle DOM events.

In React, the event objects (i.e., SyntheticEvent) that you receive in callbacks are pooled (this is now documented). This means that after the event callback has be called, the SyntheticEvent you receive will be put back in the pool with empty attributes to reduce the GC pressure.

So if you access SyntheticEvent properties asynchronously to the original callback (as may be the case if you throttle/debounce), the properties you access may be erased. If you want the event to never be put back in the pool, you can use the persist() method.

Without persist (default behavior: pooled event)

onClick = e => {
  alert(`sync -> hasNativeEvent=${!!e.nativeEvent}`);
  setTimeout(() => {
    alert(`async -> hasNativeEvent=${!!e.nativeEvent}`);
  }, 0);
};

The 2nd (async) will print hasNativeEvent=false because the event properties have been cleaned up.

With persist

onClick = e => {
  e.persist();
  alert(`sync -> hasNativeEvent=${!!e.nativeEvent}`);
  setTimeout(() => {
    alert(`async -> hasNativeEvent=${!!e.nativeEvent}`);
  }, 0);
};

The 2nd (async) will print hasNativeEvent=true because persist allows you to avoid putting the event back in the pool.

You can test these 2 behaviors here: JsFiddle

Read Julen's answer for an example of using persist() with a throttle/debounce function.


Superb answer, this is great for setting form fields state as 'interacting' for a few seconds after they stop typing, and then being able to cancel on form submit or onBlur
Note that in ES6, instead of defining your method inside the constructor (feels weird) you can do handleOnChange = debounce((e) => { /* onChange handler code here */ }, timeout) at the top level of your class. You're still effectively setting an instance member but it looks a bit more like a normal method definition. No need for a constructor if you don't already have one defined. I suppose it's mostly a style preference.
Don't forget to cancel the debounced method in componentWillUnmount: this.method.cancel() - otherwise it might want to setState on an unmounted component.
@JonasKello you can't debounce inside a stateless component because the debounced function is actually stateful. You need a stateful component to hold that debounced function, but you can call a stateless component with an already debounced function if needed.
Why all answer includes _.debounce instead of writing the function ? It needs the whole library for that function ?
O
Oliver Watkins

Uncontrolled Components

You can use the event.persist() method.

An example follows using underscore's _.debounce():

var SearchBox = React.createClass({

  componentWillMount: function () {
     this.delayedCallback = _.debounce(function (event) {
       // `event.target` is accessible now
     }, 1000);
  },

  onChange: function (event) {
    event.persist();
    this.delayedCallback(event);
  },

  render: function () {
    return (
      <input type="search" onChange={this.onChange} />
    );
  }

});

Edit: See this JSFiddle

Controlled Components

Update: the example above shows an uncontrolled component. I use controlled elements all the time so here's another example of the above, but without using the event.persist() "trickery".

A JSFiddle is available as well. Example without underscore

var SearchBox = React.createClass({
    getInitialState: function () {
        return {
            query: this.props.query
        };
    },

    componentWillMount: function () {
       this.handleSearchDebounced = _.debounce(function () {
           this.props.handleSearch.apply(this, [this.state.query]);
       }, 500);
    },

    onChange: function (event) {
      this.setState({query: event.target.value});
      this.handleSearchDebounced();
    },

    render: function () {
      return (
        <input type="search"
               value={this.state.query}
               onChange={this.onChange} />
      );
    }
});


var Search = React.createClass({
    getInitialState: function () {
        return {
            result: this.props.query
        };
    },

    handleSearch: function (query) {
        this.setState({result: query});
    },

    render: function () {
      return (
        <div id="search">
          <SearchBox query={this.state.result}
                     handleSearch={this.handleSearch} />
          <p>You searched for: <strong>{this.state.result}</strong></p>
        </div>
      );
    }
});

React.render(<Search query="Initial query" />, document.body);

Edit: updated examples and JSFiddles to React 0.12

Edit: updated examples to address the issue raised by Sebastien Lorber

Edit: updated with jsfiddle that does not use underscore and uses plain javascript debounce.


This does not work for inputs. The event target in the debounced function no longer has a value... so the input stays empty.
Slightly complex, this. You have to be a bit careful about props. If you set <input value={this.props.someprop}... then it won't render properly as the update on keypress doesn't make it back into the component until after the debounce. It's fine to omit the value= if you're happy for this to be unmanaged, but if you'd like to pre-populate the value and/or bind it somewhere else then obviously this doesn't work.
@AlastairMaw the question had an uncontrolled component, that's why the reply has it too. I've added below an alternative version for controlled components, with a pre-populated value.
this is very dangerous if you mount the component mutiple times in the DOM, see stackoverflow.com/questions/23123138/…
while this is a great answer, I don't recommend using persist especially when there may be lots of events, like on mousemove. I have seen code become totally unresponsive that way. It is much more efficient to extract the needed data from the native event in the event call, and then call the debounced / throttled function with the data only, NOT the event itself. No need to persist the event that way
A
Abra

2019: Use the 'useCallback' react hook

After trying many different approaches, I found using useCallback to be the simplest and most efficient at solving the multiple calls problem of using debounce within an onChange event.

As per the Hooks API documentation,

useCallback returns a memorized version of the callback that only changes if one of the dependencies has changed.

Passing an empty array as a dependency makes sure the callback is called only once. Here's a simple implementation :

import React, { useCallback } from "react";
import { debounce } from "lodash";

const handler = useCallback(debounce(someFunction, 2000), []);

const onChange = (event) => {
    // perform any event related action here

    handler();
 };

Hope this helps!


Excellent solution if you're using hooks. You saved me many more hours of frustration. Thanks!
Could you please explain on why the multiple calls happen in the first place? Does debounce() not consider the onChange() callback to be the same callback method?
I modified this solution to get it to work in my app. First I had to move the line const testFunc2 = useCallback(debounce((text) => console.log('testFunc2() has ran:', text), 1000) , []); inside the body of the function component or React outputs an error message about hook use outside of it. Then in the onChange event handler: <input type='text' name='name' className='th-input-container__input' onChange={evt => {testFunc2(evt.target.value);}}.
Here is how I used this solution to let user type to an input then send a debounced API call with the input value once he's done typing. stackoverflow.com/questions/59358092/….
Adding to the above answer ---- const someFunction = (text) => { dispatch({ type: "addText", payload: { id, text, }, }); }; handler(e.target.value)} />
a
andrewdotnich

After struggling with the text inputs for a while and not finding a perfect solution on my own, I found this on npm: react-debounce-input.

Here is a simple example:

import React from 'react';
import ReactDOM from 'react-dom';
import {DebounceInput} from 'react-debounce-input';

class App extends React.Component {
state = {
    value: ''
};

render() {
    return (
    <div>
        <DebounceInput
        minLength={2}
        debounceTimeout={300}
        onChange={event => this.setState({value: event.target.value})} />

        <p>Value: {this.state.value}</p>
    </div>
    );
}
}

const appRoot = document.createElement('div');
document.body.appendChild(appRoot);
ReactDOM.render(<App />, appRoot);

The DebounceInput component accepts all of the props you can assign to a normal input element. Try it out on codepen

I hope it helps someone else too and saves them some time.


After trying many solutions listed here, definitely was the easiest.
This indeed is SO much better solution! Not just because it uses least amount of code, it also allows debouncing class functions (unlike awesome-debounce-promise, which is nearly useless for that reason)
s
sledgeweight

I found this post by Justin Tulk very helpful. After a couple of attempts, in what one would perceive to be the more official way with react/redux, it shows that it fails due to React's synthetic event pooling. His solution then uses some internal state to track the value changed/entered in the input, with a callback right after setState which calls a throttled/debounced redux action that shows some results in realtime.

import React, {Component} from 'react'
import TextField from 'material-ui/TextField'
import { debounce } from 'lodash'

class TableSearch extends Component {

  constructor(props){
    super(props)

    this.state = {
        value: props.value
    }

    this.changeSearch = debounce(this.props.changeSearch, 250)
  }

  handleChange = (e) => {
    const val = e.target.value

    this.setState({ value: val }, () => {
      this.changeSearch(val)
    })
  }

  render() {

    return (
        <TextField
            className = {styles.field}
            onChange = {this.handleChange}
            value = {this.props.value}
        />
    )
  }
}

nice solution for a state component.
M
Mohan Dere

With debounce you need to keep the original synthetic event around with event.persist(). Here is working example tested with React 16+.

import React, { Component } from 'react';
import debounce from 'lodash/debounce'

class ItemType extends Component {

  evntHandler = debounce((e) => {
    console.log(e)
  }, 500);

  render() {
    return (
      <div className="form-field-wrap"
      onClick={e => {
        e.persist()
        this.evntHandler(e)
      }}>
        ...
      </div>
    );
  }
}
export default ItemType;

With functional component, you can do this -

const Search = ({ getBooks, query }) => {

  const handleOnSubmit = (e) => {
    e.preventDefault();
  }
  const debouncedGetBooks = debounce(query => {
    getBooks(query);
  }, 700);

  const onInputChange = e => {
    debouncedGetBooks(e.target.value)
  }

  return (
    <div className="search-books">
      <Form className="search-books--form" onSubmit={handleOnSubmit}>
        <Form.Group controlId="formBasicEmail">
          <Form.Control type="text" onChange={onInputChange} placeholder="Harry Potter" />
          <Form.Text className="text-muted">
            Search the world's most comprehensive index of full-text books.
          </Form.Text>
        </Form.Group>
        <Button variant="primary" type="submit">
          Search
        </Button>
      </Form>
    </div>
  )
}

References - - https://gist.github.com/elijahmanor/08fc6c8468c994c844213e4a4344a709 - https://blog.revathskumar.com/2016/02/reactjs-using-debounce-in-react-components.html


Finally a short, consistant but complete example using class component. thx!
I
Ian Kemp

If all you need from the event object is to get the DOM input element, the solution is much simpler – just use ref. Note that this requires Underscore:

class Item extends React.Component {
    constructor(props) {
        super(props);
        this.saveTitle = _.throttle(this.saveTitle.bind(this), 1000);
    }
    saveTitle(){
        let val = this.inputTitle.value;
        // make the ajax call
    }
    render() {
        return <input 
                    ref={ el => this.inputTitle = el } 
                    type="text" 
                    defaultValue={this.props.title} 
                    onChange={this.saveTitle} />
    }
}

defaultValue is what i want! Thank you very mach :)
A
Adam Pietrasiak

My solution is hooks based (written in Typescript).

I've got 2 main hooks useDebouncedValue and useDebouncedCallback

First - useDebouncedValue

Let's say we've got a search box, but we want to ask the server for search results after the user has stopped typing for 0,5s

function SearchInput() {
  const [realTimeValue, setRealTimeValue] = useState('');

  const debouncedValue = useDebouncedValue(realTimeValue, 500); // this value will pick real time value, but will change it's result only when it's seattled for 500ms

  useEffect(() => {
    // this effect will be called on seattled values
    api.fetchSearchResults(debouncedValue);
  }, [debouncedValue])

  return <input onChange={event => setRealTimeValue(event.target.value)} />
}

Implementation

import { useState, useEffect } from "react";

export function useDebouncedValue<T>(input: T, time = 500) {
  const [debouncedValue, setDebouncedValue] = useState(input);

  // every time input value has changed - set interval before it's actually commited
  useEffect(() => {
    const timeout = setTimeout(() => {
      setDebouncedValue(input);
    }, time);

    return () => {
      clearTimeout(timeout);
    };
  }, [input, time]);

  return debouncedValue;
}

Second useDebouncedCallback

It just creates a 'debounced' function in the scope of your component.

Let's say we've got a component with a button that will show alert 500ms after you stopped clicking it.

function AlertButton() {
  function showAlert() {
    alert('Clicking has seattled');
  }

  const debouncedShowAlert = useDebouncedCallback(showAlert, 500);

  return <button onClick={debouncedShowAlert}>Click</button>
}

Implementation (note I'm using lodash/debounce as a helper)

import debounce from 'lodash/debounce';
import { useMemo } from 'react';

export function useDebouncedCallback<T extends (...args: any) => any>(callback: T, wait?: number) {
  const debouncedCallback = useMemo(() => debounce(callback, wait), [callback, wait]);

  return debouncedCallback;
}

love this solution as it needs no new dependencies
d
dipenparmar12

There can be a simple approach using react hooks.

Step 1 : define a state to maintain searched text

const [searchTerm, setSearchTerm] = useState('')

Step 2 : Use useEffect to capture any change in search Term

useEffect(() => {
  const delayDebounceFn = setTimeout(() => {
    if (searchTerm) {
      // write your logic here
    }
  }, 400)

  return () => clearTimeout(delayDebounceFn)
}, [searchTerm])

Step 3 : Write a function to handle input change

function handleInputChange(value) {
  if (value) {
    setSearchTerm(value)
  }
}

That's all ! Call this method as and when required


how do you cancel it if user component was unmounted?
A
Art

There's a use-debounce package that you can use with ReactJS hooks.

From package's README:

import { useDebounce } from 'use-debounce';

export default function Input() {
  const [text, setText] = useState('Hello');
  const [value] = useDebounce(text, 1000);

  return (
    <div>
      <input
        defaultValue={'Hello'}
        onChange={(e) => {
          setText(e.target.value);
        }}
      />
      <p>Actual value: {text}</p>
      <p>Debounce value: {value}</p>
    </div>
  );
}

As you can see from the example above, it is set up to update the variable value only once every second (1000 milliseconds).


Still the best choice in January 2021
so if i want to fire an event everytime value is set, will i do it like this ? - useEffect(() => { // function here }, [value]);
c
chad steele

Lots of good info here already, but to be succinct. This works for me...

import React, {Component} from 'react';
import _ from 'lodash';

class MyComponent extends Component{
      constructor(props){
        super(props);
        this.handleChange = _.debounce(this.handleChange.bind(this),700);
      }; 

This doesn't work for me. The state does not update. If I remove _debounce wrapper it works. I love this idea though!
I'd have to see your code to offer much here, but I suspect there's something else going on... hopefully this much more thorough answer will shed some light. stackoverflow.com/questions/23123138/…
Worked like a charm for me. Wrapped the bound handler function as above, then updated the state in the handler function based on the field input. Thanks!
M
Matt

If you are using redux you can do this in a very elegant way with middleware. You can define a Debounce middleware as:

var timeout;
export default store => next => action => {
  const { meta = {} } = action;
  if(meta.debounce){
    clearTimeout(timeout);
    timeout = setTimeout(() => {
      next(action)
    }, meta.debounce)
  }else{
    next(action)
  }
}

You can then add debouncing to action creators, such as:

export default debouncedAction = (payload) => ({
  type : 'DEBOUNCED_ACTION',
  payload : payload,
  meta : {debounce : 300}
}

There's actually already middleware you can get off npm to do this for you.


i think this middleware must be the first one to be executed in applyMiddleware(...) chain if we have many
The timeout isn't initialized and that first clearTimeout will be dealing with undefined for a param. Not good.
S
STEEL

Using ES6 CLASS and React 15.x.x & lodash.debounce Im using React's refs here since event losses the this bind internally.

class UserInput extends React.Component { constructor(props) { super(props); this.state = { userInput: "" }; this.updateInput = _.debounce(this.updateInput, 500); } updateInput(userInput) { this.setState({ userInput }); //OrderActions.updateValue(userInput);//do some server stuff } render() { return (

User typed: { this.state.userInput }

this.updateInput(this.refs.userValue.value) } type = "text" / >
); } } ReactDOM.render( < UserInput / > , document.getElementById('root') );


D
Dinesh Madanlal

You can use Lodash debounce https://lodash.com/docs/4.17.5#debounce method. It is simple and effective.

import * as lodash from lodash;

const update = (input) => {
    // Update the input here.
    console.log(`Input ${input}`);     
}

const debounceHandleUpdate = lodash.debounce((input) => update(input), 200, {maxWait: 200});

doHandleChange() {
   debounceHandleUpdate(input);
}

You can also cancel the debounce method by using the below method.

this.debounceHandleUpdate.cancel();

Hope it helps you. Cheers!!


k
kenju

FYI

Here is another PoC implementation:

without any libraries (e.g. lodash) for debouncing

using React Hooks API

I hope it helps :)

import React, { useState, useEffect, ChangeEvent } from 'react';

export default function DebouncedSearchBox({
  inputType,
  handleSearch,
  placeholder,
  debounceInterval,
}: {
  inputType?: string;
  handleSearch: (q: string) => void;
  placeholder: string;
  debounceInterval: number;
}) {
  const [query, setQuery] = useState<string>('');
  const [timer, setTimer] = useState<NodeJS.Timer | undefined>();

  useEffect(() => {
    if (timer) {
      clearTimeout(timer);
    }
    setTimer(setTimeout(() => {
      handleSearch(query);
    }, debounceInterval));
  }, [query]);

  const handleOnChange = (e: ChangeEvent<HTMLInputElement>): void => {
    setQuery(e.target.value);
  };

  return (
    <input
      type={inputType || 'text'}
      className="form-control"
      placeholder={placeholder}
      value={query}
      onChange={handleOnChange}
    />
  );
}

R
Rebs

There is now another solution for React and React Native in late/2019:

react-debounce-component

<input>
<Debounce ms={500}>
  <List/>
</Debounce>

It's a component, easy to use, tiny and widley supported

Example:

https://i.stack.imgur.com/ptVlA.gif

import React from 'react';
import Debounce from 'react-debounce-component';

class App extends React.Component {
  constructor (props) {
    super(props);
    this.state = {value: 'Hello'}
  }
  render () {
    return (
      <div>
        <input value={this.state.value} onChange={(event) => {this.setState({value: event.target.value})}}/>
        <Debounce ms={1000}>
          <div>{this.state.value}</div>
        </Debounce>
      </div>
    );
  }
}

export default App;

*I'm the creator of this component


X
Xinan

I can't find any answers under this question mentioning the approach I am using so just want to provide an alternative solution here which I think is the best for my use case.

If you are using the popular react hooks toolkit lib called react-use, then there is a utility hook called useDebounce() that implemented denounce logic in a quite elegant way.

const [query, setQuery] = useState('');

useDebounce(
  () => {
    emitYourOnDebouncedSearchEvent(query);
  },
  2000,
  [query]
);

return <input onChange={({ currentTarget }) => setQuery(currentTarget.value)} />

For details please check the lib's github page directly.

https://github.com/streamich/react-use/blob/master/docs/useDebounce.md


O
Or Assayag

As for June 2021, You can simply implement xnimorz solution: https://github.com/xnimorz/use-debounce

import { useState, useEffect, useRef } from "react";
// Usage
function App() {
  // State and setters for ...
  // Search term
  const [searchTerm, setSearchTerm] = useState("");
  // API search results
  const [results, setResults] = useState([]);
  // Searching status (whether there is pending API request)
  const [isSearching, setIsSearching] = useState(false);
  // Debounce search term so that it only gives us latest value ...
  // ... if searchTerm has not been updated within last 500ms.
  // The goal is to only have the API call fire when user stops typing ...
  // ... so that we aren't hitting our API rapidly.
  const debouncedSearchTerm = useDebounce(searchTerm, 500);
  // Effect for API call
  useEffect(
    () => {
      if (debouncedSearchTerm) {
        setIsSearching(true);
        searchCharacters(debouncedSearchTerm).then((results) => {
          setIsSearching(false);
          setResults(results);
        });
      } else {
        setResults([]);
        setIsSearching(false);
      }
    },
    [debouncedSearchTerm] // Only call effect if debounced search term changes
  );
  return (
    <div>
      <input
        placeholder="Search Marvel Comics"
        onChange={(e) => setSearchTerm(e.target.value)}
      />
      {isSearching && <div>Searching ...</div>}
      {results.map((result) => (
        <div key={result.id}>
          <h4>{result.title}</h4>
          <img
            src={`${result.thumbnail.path}/portrait_incredible.${result.thumbnail.extension}`}
          />
        </div>
      ))}
    </div>
  );
}
// API search function
function searchCharacters(search) {
  const apiKey = "f9dfb1e8d466d36c27850bedd2047687";
  return fetch(
    `https://gateway.marvel.com/v1/public/comics?apikey=${apiKey}&titleStartsWith=${search}`,
    {
      method: "GET",
    }
  )
    .then((r) => r.json())
    .then((r) => r.data.results)
    .catch((error) => {
      console.error(error);
      return [];
    });
}
// Hook
function useDebounce(value, delay) {
  // State and setters for debounced value
  const [debouncedValue, setDebouncedValue] = useState(value);
  useEffect(
    () => {
      // Update debounced value after delay
      const handler = setTimeout(() => {
        setDebouncedValue(value);
      }, delay);
      // Cancel the timeout if value changes (also on delay change or unmount)
      // This is how we prevent debounced value from updating if value is changed ...
      // .. within the delay period. Timeout gets cleared and restarted.
      return () => {
        clearTimeout(handler);
      };
    },
    [value, delay] // Only re-call effect if value or delay changes
  );
  return debouncedValue;
}

S
Silicum Silium

A nice and clean solution, that doesn't require any external dependencies:

Debouncing with React Hooks

It uses a custom plus the useEffect React hooks and the setTimeout / clearTimeout method.


s
superluminary

2022 - use a useEffect hook

Your best option at this time is to use the useEffect hook. useEffect lets you set a function that can modify state in response to some async event. Debouncing is asynchronous so useEffect works nicely for this purpose.

If you return a function from the hook, the returned function will be called before the hook is called again. This lets you cancel the previous timeout, effectively debouncing the function.

Example

Here we have two states, value and tempValue. Setting tempValue will trigger a useEffect hook that will start a 1000ms timeout which will call a function to copy tempValue into value.

The hook returns a function that unsets the timer. When the hook is called again (i.e. another key is pressed) the timeout is canceled and reset.

const DebounceDemo = () => {
  const [value, setValue] = useState();
  const [tempValue, setTempValue] = useState();

  // This hook will set a 1000 ms timer to copy tempValue into value
  // If the hook is called again, the timer will be cancelled
  // This creates a debounce
  useEffect(
    () => {
      // Wait 1000ms before copying the value of tempValue into value;
      const timeout = setTimeout(() => {
        setValue(tempValue);
      }, 1000);

      // If the hook is called again, cancel the previous timeout
      // This creates a debounce instead of a delay
      return () => clearTimeout(timeout);
    },
    // Run the hook every time the user makes a keystroke
    [tempValue]
  )

  // Here we create an input to set tempValue. 
  // value will be updated 1000 ms after the hook is last called, 
  // i.e after the last user keystroke.
  return (
    <>
      <input 
        onChange={
          ({ target }) => setTempValue(target.value)
        }
      />
      <p>{ value }</p>
    </>
  )
}

Thanks for great answer. There is small typo setValue(tempvalue) -> setValue(tempValue)
cancelTimeout should be clearTimeout
@Cafn - updated. Thanks for spotting
p
puchu

Just another variant with recent react and lodash.

class Filter extends Component {
  static propTypes = {
    text: PropTypes.string.isRequired,
    onChange: PropTypes.func.isRequired
  }

  state = {
    initialText: '',
    text: ''
  }

  constructor (props) {
    super(props)

    this.setText = this.setText.bind(this)
    this.onChange = _.fp.debounce(500)(this.onChange.bind(this))
  }

  static getDerivedStateFromProps (nextProps, prevState) {
    const { text } = nextProps

    if (text !== prevState.initialText) {
      return { initialText: text, text }
    }

    return null
  }

  setText (text) {
    this.setState({ text })
    this.onChange(text)
  }

  onChange (text) {
    this.props.onChange(text)
  }

  render () {
    return (<input value={this.state.text} onChange={(event) => this.setText(event.target.value)} />)
  }
}

Z
Zhivko Zhelev

Did you try?

function debounce(fn, delay) {
  var timer = null;
  return function() {
    var context = this,
      args = arguments;
    clearTimeout(timer);
    timer = setTimeout(function() {
      fn.apply(context, args);
    }, delay);
  };
}

var SearchBox = React.createClass({
  render: function() {
    return <input type="search" name="p" onChange={this.handleOnChange} />;
  },

  handleOnChange: function(event) {
    debounce(\\ Your handleChange code , 200);
  }
});

Is this at all different from the original poster's solution?
Yes, it's different here: debounce(handleChange , 200);
R
Robert

Instead of wrapping the handleOnChange in a debounce(), why not wrap the ajax call inside the callback function inside the debounce, thereby not destroying the event object. So something like this:

handleOnChange: function (event) {
   debounce(
     $.ajax({})
  , 250);
}

Because the event object is not immutable and is destroyed by ReactJS, so even if you wrap and attain a closure capture, the code will fail.
m
mlucool

Here is an example I came up with that wraps another class with a debouncer. This lends itself nicely to being made into a decorator/higher order function:

export class DebouncedThingy extends React.Component {
    static ToDebounce = ['someProp', 'someProp2'];
    constructor(props) {
        super(props);
        this.state = {};
    }
    // On prop maybe changed
    componentWillReceiveProps = (nextProps) => {
        this.debouncedSetState();
    };
    // Before initial render
    componentWillMount = () => {
        // Set state then debounce it from here on out (consider using _.throttle)
        this.debouncedSetState();
        this.debouncedSetState = _.debounce(this.debouncedSetState, 300);
    };
    debouncedSetState = () => {
        this.setState(_.pick(this.props, DebouncedThingy.ToDebounce));
    };
    render() {
        const restOfProps = _.omit(this.props, DebouncedThingy.ToDebounce);
        return <Thingy {...restOfProps} {...this.state} />
    }
}

T
Thread Pitt

Here's a snippet using @Abra's approach wrapped in a function component (we use fabric for the UI, just replace it with a simple button)

import React, { useCallback } from "react";
import { debounce } from "lodash";

import { PrimaryButton, DefaultButton } from 'office-ui-fabric-react/lib/Button';

const debounceTimeInMS = 2000;

export const PrimaryButtonDebounced = (props) => {

    const debouncedOnClick = debounce(props.onClick, debounceTimeInMS, { leading: true });

    const clickHandlerDebounced = useCallback((e, value) => {

        debouncedOnClick(e, value);

    },[]);

    const onClick = (e, value) => {

        clickHandlerDebounced(e, value);
    };

    return (
        <PrimaryButton {...props}
            onClick={onClick}
        />
    );
}

F
Francisco Hanna

Met this problem today. Solved it using setTimeout and clearTimeout.

I will give an example that you could adapt:

import React, { Component } from 'react'

const DEBOUNCE_TIME = 500

class PlacesAutocomplete extends Component {
  debounceTimer = null;

  onChangeHandler = (event) => {
    // Clear the last registered timer for the function
    clearTimeout(this.debounceTimer);

    // Set a new timer
    this.debounceTimer = setTimeout(
      // Bind the callback function to pass the current input value as arg
      this.getSuggestions.bind(null, event.target.value), 
      DEBOUNCE_TIME
    )
  }

  // The function that is being debounced
  getSuggestions = (searchTerm) => {
    console.log(searchTerm)
  }

  render() {
    return (
      <input type="text" onChange={this.onChangeHandler} />
    )
  }
}

export default PlacesAutocomplete

You could also refactor it in it's own function component:

import React from 'react'

function DebouncedInput({ debounceTime, callback}) {
  let debounceTimer = null
  return (
    <input type="text" onChange={(event) => {
      clearTimeout(debounceTimer);

      debounceTimer = setTimeout(
        callback.bind(null, event.target.value), 
        debounceTime
      )
    }} />
  )
}

export default DebouncedInput

And use it like:

import React, { Component } from 'react'
import DebouncedInput from '../DebouncedInput';

class PlacesAutocomplete extends Component {
  debounceTimer = null;

  getSuggestions = (searchTerm) => {
    console.log(searchTerm)
  }

  render() {
    return (
      <DebouncedInput debounceTime={500} callback={this.getSuggestions} />
    )
  }
}

export default PlacesAutocomplete

u
user1079877

This solution does not need any extra lib and it also fires things up when the user presses enter:

const debounce = (fn, delay) => {
    let timer = null;
    return function() {
        const context = this,
        args = arguments;
        clearTimeout(timer);
        timer = setTimeout(() => {
            fn.apply(context, args);
        }, delay);
    };  
}

const [search, setSearch] = useState('');
const [searchFor, setSearchFor] = useState(search);

useEffect(() => {
    console.log("Search:", searchFor);
}, [searchFor]);

const fireChange = event => {
    const { keyCode } = event;
    if (keyCode === 13) {
        event.preventDefault();
        setSearchFor(search);
    }
}

const changeSearch = event => {
    const { value } = event.target;
    setSearch(value);
    debounceSetSearchFor(value);
};

const debounceSetSearchFor = useCallback(debounce(function(value) {
    setSearchFor(value);
}, 250), []);

and the input could be like:

<input value={search} onKeyDown={fireChange} onChange={changeSearch}  />

Pureeeeeeeee JS, Love it
G
Gerson Diniz

Hook:

import {useState} from "react";

const useDebounce = ({defaultTimeout = 250, defaultIdentifier = 'default'} = {}) => {

    const [identifiers, setIdentifiers] = useState({[defaultIdentifier]: null});

    return ({fn = null, identifier = defaultIdentifier, timeout = defaultTimeout} = {}) => {
        if (identifiers.hasOwnProperty(identifier)) clearTimeout(identifiers[identifier]);
        setIdentifiers({...identifiers, [identifier]: setTimeout(fn, timeout)});
    };
};

export default useDebounce;

And use it anywhere (in same file use identifier to prevent concurrence) like:

const debounce = useDebounce();

const handlerA = () => {
    debounce({fn: () => console.log('after 2000ms of last call with identifier A'), identifier: 'A', timeout: 2000});
};

const handlerB = () => {
    debounce({fn: () => console.log('after 1500ms of last call with identifier B'), identifier: 'B', timeout: 1500});
};

looks nice, if i understand right a use-case can look like the following snippet: const debounce = useDebounce(); const debouncedSearchInputHandler = (event) => { setSearchInput(event.target.value); debounce({fn: () => startRestCall(event.target.value), timeout: 1000}); };
S
Siva Kannan

simple and effective
https://www.npmjs.com/package/use-debounce
use-debounce

import { useDebouncedCallback } from 'use-debounce';

function Input({ defaultValue }) {
  const [value, setValue] = useState(defaultValue);
  const debounced = useDebouncedCallback(
    (value) => {
      setValue(value);
    },
    // delay
    1000
  );

  return (
    <div>
      <input defaultValue={defaultValue} onChange={(e) => debounced(e.target.value)} />
      <p>Debounced value: {value}</p>
    </div>
  );
}

Please add comments for the downvoting, I have been using this code in my current app and its perfectly working
This only sends the last letter entered
E
Edward

I was searching for a solution to the same problem and came across this thread as well as some others but they had the same problem: if you are trying to do a handleOnChange function and you need the value from an event target, you will get cannot read property value of null or some such error. In my case, I also needed to preserve the context of this inside the debounced function since I'm executing a fluxible action. Here's my solution, it works well for my use case so I'm leaving it here in case anyone comes across this thread:

// at top of file:
var myAction = require('../actions/someAction');

// inside React.createClass({...});

handleOnChange: function (event) {
    var value = event.target.value;
    var doAction = _.curry(this.context.executeAction, 2);

    // only one parameter gets passed into the curried function,
    // so the function passed as the first parameter to _.curry()
    // will not be executed until the second parameter is passed
    // which happens in the next function that is wrapped in _.debounce()
    debouncedOnChange(doAction(myAction), value);
},

debouncedOnChange: _.debounce(function(action, value) {
    action(value);
}, 300)