秒表计时器的实现：
效果图如下：
附代码，已调试运行
<!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">
<title>Document</title>
<style>
#div1 {
width: 300px;
height: 400px;
background: skyblue;
margin: 100px auto;
text-align: center;
}
#count {
width: 200px;
height: 150px;
line-height: 150px;
margin: auto;
font-size: 40px;
}
#div1 input {
width: 150px;
height: 40px;
background: orange;
font-size: 25px;
margin-top: 20px
}
</style>
</head>
<body>
<div id="div1">
<div id="count">
<span id="id_H">00</span>
<span id="id_M">00</span>
<span id="id_S">00</span>
</div>
<input id="start" type="button" value="开始">
<input id="pause" type="button" value="暂停">
<input id="stop" type="button" value="停止">
</div>
<script>
//可以将查找标签节点的操作进行简化 var btn = getElementById('btn')
function $(id) {
return document.getElementById(id)
}
window.onload = function() {
//点击开始建 开始计数
var count = 0
var timer = null //timer变量记录定时器setInterval的返回值
$("start").onclick = function() {
timer = setInterval(function() {
count++;
console.log(count)
// 需要改变页面上时分秒的值
console.log($("id_S"))
$("id_S").innerHTML = showNum(count % 60)
$("id_M").innerHTML = showNum(parseInt(count / 60) % 60)
$("id_H").innerHTML = showNum(parseInt(count / 60 / 60))
}, 1000)
}
$("pause").onclick = function() {
//取消定时器
clearInterval(timer)
}
//停止记数 数据清零 页面展示数据清零
$("stop").onclick = function() {
//取消定时器
$("pause").onclick()
// clearInterval(timer)
//数据清零 总秒数清零
count = 0
//页面展示数据清零
$("id_S").innerHTML = "00"
$("id_M").innerHTML = "00"
$("id_H").innerHTML = "00"
}
//封装一个处理单位数字的函数
function showNum(num) {
if (num < 10) {
return '0' + num
}
return num
}
}
</script>
</body>
</html>
