如何在React.js中执行debounce ?

我想撤消handleOnChange。

我尝试debounce(这。handleOnChange, 200)但它不起作用。

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
  }
});

当前回答

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)

其他回答

这个解决方案不需要任何额外的库,它也会在用户按下enter时启动:

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), []);

输入可以是这样的:

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

至于2021年6月,您可以简单地实现xnimorz解决方案: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;
}

下面是我想出的一个用debouncer包装另一个类的例子。这使得自己很好地成为一个装饰器/高阶函数:

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} />
    }
}

您可以使用引用变量来存储计时器,然后将其清除。下面是一个不使用任何第三方包在react中实现deboundation的例子

import { useState, useRef } from "react";
import "./styles.css";

export default function App() {
  // Variables for debouncing
  const [text, setText] = useState("");
  const timer = useRef();

  // Variables for throtteling
  const [throttle, setThrottle] = useState(false)


  const handleDebouncing = ({ target }) => {
    clearTimeout(timer.current)

    timer.current = setTimeout(() => {
      callApi();
    }, 300);

    setText(target.value);
  };

  const handleThrottleing = () => {
    callApi()

    setThrottle(true)

    setTimeout(() => {
      setThrottle(false)
    }, 2000)
  }

  const callApi = () => {
    console.log("Calling Api");
  };

  return (
    <div className="App">
      <input type="text" onChange={handleDebouncing} />

      <button onClick={handleThrottleing} disabled={throttle} >Click me to see throtteling</button>
    </div>
  );
}

今天遇到了这个问题。使用setTimeout和clearTimeout解决。

我将给出一个你可以适应的例子:

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

你也可以在它自己的函数组件中重构它:

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

像这样使用它:

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