<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<style>
.container {
width: 300px;
height: 100px;
background-color: #eee;
padding: 20px 10px;
margin: 100px auto;
}
.box {
width: 100px;
height: 30px;
margin: 30px auto;
}
.box span {
color: red;
font-size: 20px;
display: inline-block;
padding: 0 5px;
}
</style>
<title>Document</title>
</head>
<body>
<div class="container">
<input type="number" id="time" />
<button id="btn1">计时开始</button>
<button id="btn2">暂停</button>
<button id="btn3">结束</button>
<div class="box">倒计时<span></span>秒</div>
</div>
</body>
<script>
var time = document.querySelector('#time')
var btn1 = document.querySelector('#btn1')
var btn2 = document.querySelector('#btn2')
var btn3 = document.querySelector('#btn3')
var span = document.querySelector('.box').children[0]
// 计时
btn1.addEventListener('click', function() {
var val = time.value
time.value = ''
if (!val) {
alert('请输如大于0的时间，单位：秒')
} else {
var timeId = funTime(val)
}
// 暂停
btn2.addEventListener('click', function() {
var txt = btn2.innerHTML
if (span.innerHTML) {
if (txt == '暂停') {
clearInterval(timeId)
btn2.innerHTML = '开始'
} else {
timeId = funTime(span.innerHTML)
btn2.innerHTML = '暂停'
}
}
})
// 结束
btn3.addEventListener('click', function() {
if (timeId) {
clearInterval(timeId)
span.innerHTML = ''
}
})
// 计时器函数
function funTime(val) {
span.innerHTML = val
var timer = setInterval(() => {
if (val === 0) {
clearInterval(timeId)
span.innerHTML = ''
alert('时间到！')
} else {
val--
span.innerHTML = val
}
}, 1000)
return timer
}
})
</script>
</html>
JS实现简易计时器
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