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

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;
}

其他回答

你试过吗?

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);
  }
});

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} />
    }
}

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;
}

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>
  );
}

Julen的解决方案有点难以阅读,这里有更清晰和准确的反应代码,供那些根据标题而不是问题的微小细节绊倒他的人使用。

Tl;dr版本:当你要更新到观察者发送调用一个调度方法,反过来实际上会通知观察者(或执行ajax等)

使用示例组件jsfiddle完成jsfiddle

var InputField = React.createClass({

    getDefaultProps: function () {
        return {
            initialValue: '',
            onChange: null
        };
    },

    getInitialState: function () {
        return {
            value: this.props.initialValue
        };
    },

    render: function () {
        var state = this.state;
        return (
            <input type="text"
                   value={state.value}
                   onChange={this.onVolatileChange} />
        );
    },

    onVolatileChange: function (event) {
        this.setState({ 
            value: event.target.value 
        });

        this.scheduleChange();
    },

    scheduleChange: _.debounce(function () {
        this.onChange();
    }, 250),

    onChange: function () {
        var props = this.props;
        if (props.onChange != null) {
            props.onChange.call(this, this.state.value)
        }
    },

});