Javascript 无法清除设置间隔
我想在单击停止按钮时清除间隔,似乎clearInterval没有按预期工作。触发handleStop功能或handleReset id时,计时器不会停止 以下是我正在尝试做的:Javascript 无法清除设置间隔,javascript,reactjs,dom-events,Javascript,Reactjs,Dom Events,我想在单击停止按钮时清除间隔,似乎clearInterval没有按预期工作。触发handleStop功能或handleReset id时,计时器不会停止 以下是我正在尝试做的: import React from "react" import useApp from "../App" import Interact from "./Interact"; const Timer = () => { let tim
import React from "react"
import useApp from "../App"
import Interact from "./Interact";
const Timer = () => {
let timer;
const {millisec , setMillisec , sec , setSec , min , setMin , hr , setHr} = useApp();
const handleStart = () => {
timer = setInterval(() => {
setMillisec((prev) => {
if (prev === 100) {
setSec((prevB) =>{
if(prevB === 60){
setMin(prevC => {
if(prevC === 60){
setHr(prevD => prevD + 1)
return 0
}
return prevC + 1
})
return 0
}
return prevB + 1
});
return 0;
}
return prev + 1;
});
}, 10);
};
const handleStop = () => {
clearInterval(timer)
}
const handleReset = () => {
clearInterval(timer)
setMillisec(0)
setSec(0)
setMin(0)
setHr(0)
}
return(
<>
<div className="parent">
<div className="main">
<h1 className="heading">Stop Watch</h1>
<div className="timer">
<div className ="hour">{hr}</div>
<div className ="min">{min}</div>
<div className ="sec">{sec}</div>
<div className ="millisec">{millisec}</div>
</div>
<Interact handleStart = {handleStart}
handleStop = {handleStop}
handleReset ={handleReset}
/>
</div>
</div>
</>
)
}
export default Timer
当需要中断设置间隔时,将设置间隔传递给clearInterval。每次呈现计时器组件时,变量计时器都会重新声明。因此,setInterval参考被重置 您可以在全局范围内声明计时器,如
...
import Interact from "./Interact";
let timer;
const Timer = () => {
const {millisec , setMillisec , sec , setSec , min , setMin , hr , setHr} = useApp();
const handleStart = () => {
...
或者也可以使用react钩子来维护setInterwal引用。就像我所做的那样,我将setInterval存储在一个名为timer的变量中,然后将timer传递给clearInterval,但它不起作用。请注意,这意味着您只能有一个