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
}
});
/**
* Returns a function with the same signature of input `callback` (but without an output) that if called, smartly
* executes the `callback` in a debounced way.<br>
* There is no `delay` (to execute the `callback`) in the self-delayed tries (try = calling debounced callback). It
* will defer **only** subsequent tries (that are earlier than a minimum timeout (`delay` ms) after the latest
* execution). It also **cancels stale tries** (that have been obsoleted because of creation of newer tries during the
* same timeout).<br>
* The timeout won't be expanded! So **the subsequent execution won't be deferred more than `delay`**, at all.
* @param {Function} callback
* @param {number} [delay=167] Defaults to `167` that is equal to "10 frames at 60 Hz" (`10 * (1000 / 60) ~= 167 ms`)
* @return {Function}
*/
export function smartDebounce (callback, delay = 167) {
let minNextExecTime = 0
let timeoutId
function debounced (...args) {
const now = new Date().getTime()
if (now > minNextExecTime) { // execute immediately
minNextExecTime = now + delay // there would be at least `delay` ms between ...
callback.apply(this, args) // ... two consecutive executions
return
}
// schedule the execution:
clearTimeout(timeoutId) // unset possible previous scheduling
timeoutId = setTimeout( // set new scheduling
() => {
minNextExecTime = now + delay // there would be at least `delay` ms between ...
callback.apply(this, args) // ... two consecutive executions
},
minNextExecTime - now, // 0 <= timeout <= `delay` ... (`minNextExecTime` <= `now` + `delay`)
)
}
debounced.clear = clearTimeout.bind(null, timeoutId)
return debounced
}
/**
* Like React's `useCallback`, but will {@link smartDebounce smartly debounce} future executions.
* @param {Function} callback
* @param {[]} deps
* @param {number} [delay=167] - Defaults to `167` that is equal to "10 frames at 60 Hz" (`10 * (1000 / 60) ~= 167 ms`)
*/
export const useDebounced = (callback, deps, delay = 167) =>
useMemo(() => smartDebounce(callback, delay), [...deps, delay])
下面是一个使用@Abra方法封装在函数组件中的代码片段
(我们使用织物的UI,只是用一个简单的按钮替换它)
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}
/>
);
}
避免使用event.persist()——你想让React回收合成事件。我认为无论你使用类还是钩子,最干净的方法是将回调函数分成两部分:
没有deboundation的回调
只使用您需要的事件片段调用已撤销的函数(这样合成的事件就可以循环使用)
类
handleMouseOver = throttle(target => {
console.log(target);
}, 1000);
onMouseOver = e => {
this.handleMouseOver(e.target);
};
<div onMouseOver={this.onMouseOver} />
功能
const handleMouseOver = useRef(throttle(target => {
console.log(target);
}, 1000));
function onMouseOver(e) {
handleMouseOver.current(e.target);
}
<div onMouseOver={this.onMouseOver} />
注意,如果你的handleMouseOver函数从组件中使用状态,你应该使用usemo而不是useRef,并将它们作为依赖项传递,否则你将使用过时的数据(当然不适用于类)。
对于throttle或debounce,最好的方法是创建一个函数生成器,这样你就可以在任何地方使用它,例如:
updateUserProfileField(fieldName) {
const handler = throttle(value => {
console.log(fieldName, value);
}, 400);
return evt => handler(evt.target.value.trim());
}
在你的渲染方法中,你可以这样做:
<input onChange={this.updateUserProfileField("givenName").bind(this)}/>
updateUserProfileField方法将在每次调用它时创建一个单独的函数。
注意不要尝试直接返回处理程序,例如,这将不起作用:
updateUserProfileField(fieldName) {
return evt => throttle(value => {
console.log(fieldName, value);
}, 400)(evt.target.value.trim());
}
为什么这将不会工作的原因,因为这将生成一个新的油门函数每次事件调用而不是使用相同的油门函数,所以基本上油门将是无用的;)
此外,如果你使用debounce或throttle,你不需要setTimeout或clearTimeout,这实际上是我们使用它们的原因:P