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
}
});
如果你只需要在一个按钮中执行一个请求数据的debounce,提供的代码可能对你有帮助:
创建一个函数,以防止在请求为真或假时使用默认的条件语句
实现useState钩子和useEffect钩子
const PageOne = () => {
const [requesting, setRequesting] = useState(false);
useEffect(() => {
return () => {
setRequesting(false);
};
}, [requesting]);
const onDebounce = (e) => {
if (requesting === true) {
e.preventDefault();
}
// ACTIONS
setLoading(true);
};
return (
<div>
<button onClick={onDebounce}>Requesting data</button>
</div>
)
}
在与文本输入斗争了一段时间后,我自己没有找到一个完美的解决方案,我在npm上发现了这个:react-debounce-input。
这里有一个简单的例子:
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);
DebounceInput组件接受您可以分配给普通输入元素的所有道具。在codeen上试试吧
我希望这也能帮助其他人,节省他们的时间。
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>
);
}
});
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});
};
使用React Hooks和响应式编程(RxJS)的React ajax debounce和cancel示例解决方案:
import React, { useEffect, useState } from "react";
import { ajax } from "rxjs/ajax";
import { debounceTime, delay, takeUntil } from "rxjs/operators";
import { Subject } from "rxjs/internal/Subject";
const App = () => {
const [items, setItems] = useState([]);
const [loading, setLoading] = useState(true);
const [filterChangedSubject] = useState(() => {
// Arrow function is used to init Singleton Subject. (in a scope of a current component)
return new Subject<string>();
});
useEffect(() => {
// Effect that will be initialized once on a react component init.
const subscription = filterChangedSubject
.pipe(debounceTime(200))
.subscribe((filter) => {
if (!filter) {
setLoading(false);
setItems([]);
return;
}
ajax(`https://swapi.dev/api/people?search=${filter}`)
.pipe(
// current running ajax is canceled on filter change.
takeUntil(filterChangedSubject)
)
.subscribe(
(results) => {
// Set items will cause render:
setItems(results.response.results);
},
() => {
setLoading(false);
},
() => {
setLoading(false);
}
);
});
return () => {
// On Component destroy. notify takeUntil to unsubscribe from current running ajax request
filterChangedSubject.next("");
// unsubscribe filter change listener
subscription.unsubscribe();
};
}, []);
const onFilterChange = (e) => {
// Notify subject about the filter change
filterChangedSubject.next(e.target.value);
};
return (
<div>
Cards
{loading && <div>Loading...</div>}
<input onChange={onFilterChange}></input>
{items && items.map((item, index) => <div key={index}>{item.name}</div>)}
</div>
);
};
export default App;