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
}
});
2022 -使用useEffect钩子
此时最好的选择是使用useEffect钩子。useEffect允许您设置一个函数,该函数可以修改状态以响应某些异步事件。debounging是异步的,因此useEffect可以很好地用于此目的。
如果从钩子返回一个函数,返回的函数将在钩子再次被调用之前被调用。这让您可以取消之前的超时,有效地解除函数。
例子
这里我们有两个状态,value和tempValue。设置tempValue将触发useEffect钩子,该钩子将启动一个1000ms超时,该超时将调用一个函数将tempValue复制为value。
钩子返回一个取消定时器设置的函数。当钩子再次被调用时(即按下另一个键),超时被取消并重置。
const DebounceDemo = () => {
const [value, setValue] = useState();
const [tempValue, setTempValue] = useState();
// This hook will set a 1000 ms timer to copy tempValue into value
// If the hook is called again, the timer will be cancelled
// This creates a debounce
useEffect(
() => {
// Wait 1000ms before copying the value of tempValue into value;
const timeout = setTimeout(() => {
setValue(tempValue);
}, 1000);
// If the hook is called again, cancel the previous timeout
// This creates a debounce instead of a delay
return () => clearTimeout(timeout);
},
// Run the hook every time the user makes a keystroke
[tempValue]
)
// Here we create an input to set tempValue.
// value will be updated 1000 ms after the hook is last called,
// i.e after the last user keystroke.
return (
<>
<input
onChange={
({ target }) => setTempValue(target.value)
}
/>
<p>{ value }</p>
</>
)
}
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)
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
我们需要将setter传递给debpublished方法:
以下是StackBlitz的一个例子:
import React from "react";
import debounce from "lodash/debounce";
export default function App() {
const [state, setState] = React.useState({
debouncedLog: ""
});
const debouncedLog = React.useCallback(
debounce((setState, log) => {
setState(prevState => ({
...prevState,
debouncedLog: log
}));
}, 500),
[]
);
const onChange = React.useCallback(({ target: { value: log } }) => {
debouncedLog(setState, log); // passing the setState along...
}, []);
return (
<div>
<input onChange={onChange} style={{ outline: "1px blue solid" }} />
<pre>Debounced Value: {state.debouncedLog}</pre>
</div>
);
}
祝你好运…