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
}
});
看点:
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;
并在任何地方使用它(在同一个文件中使用标识符以防止并发),例如:
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});
};
你也可以使用自己编写的mixin,就像这样:
var DebounceMixin = {
debounce: function(func, time, immediate) {
var timeout = this.debouncedTimeout;
if (!timeout) {
if (immediate) func();
this.debouncedTimeout = setTimeout(function() {
if (!immediate) func();
this.debouncedTimeout = void 0;
}.bind(this), time);
}
}
};
然后像这样在你的组件中使用它:
var MyComponent = React.createClass({
mixins: [DebounceMixin],
handleClick: function(e) {
this.debounce(function() {
this.setState({
buttonClicked: true
});
}.bind(this), 500, true);
},
render: function() {
return (
<button onClick={this.handleClick}></button>
);
}
});
有一个使用react钩子的简单方法。
步骤1:定义一个状态来维护搜索的文本
const [searchTerm, setSearchTerm] = useState('')
步骤2:使用useEffect捕获搜索Term中的任何变化
useEffect(() => {
const delayDebounceFn = setTimeout(() => {
if (searchTerm) {
// write your logic here
}
}, 400)
return () => clearTimeout(delayDebounceFn)
}, [searchTerm])
步骤3:编写一个函数来处理输入更改
function handleInputChange(value) {
if (value) {
setSearchTerm(value)
}
}
就这些!在需要时调用此方法
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)
对于debounce,你需要在event.persist()中保留原始的合成事件。下面是用React 16+测试的工作示例。
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;
使用功能组件,您可以做到这一点-
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>
)
}
引用- - - - - -
——https://gist.github.com/elijahmanor/08fc6c8468c994c844213e4a4344a709
——https://blog.revathskumar.com/2016/02/reactjs-using-debounce-in-react-components.html