<!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>
#progress{
position: relative;
margin: auto;
top: 200px;
display: block;
200px;
height: 20px;
border-style: dotted;
border- thin;
border-color: darkgreen;
}
#filldiv{
position:absolute;
top: 0px;
left: 0px;
0px;
height: 20px;
background: blue;
}
#percent{
position: absolute;
top: 0px;
left: 200px;
}
</style>
</head>
<body>
<div id="progress">
<div id="filldiv"></div>
<span id="percent">0</span>
</div>
<script>
// 原理就是让里面的div随着定时器 让他的width慢慢增加
// 获取需要操作的dom对象
var $progress = document.querySelector('#progress');
var $filldiv = document.querySelector('#filldiv');
var $percent = document.querySelector('#percent');
// 设置定时器
var timer = setInterval(function () {
$filldiv.style.width = $filldiv.offsetWidth + 1 + 'px';
// 设置百分比与进度条同步
$percent.innerHTML = parseInt(($filldiv.offsetWidth/200)*100) + "%";
// 当进度条走到顶端 清除定时器
if ($filldiv.offsetWidth == 200) {
clearInterval(timer);
}
},20);
</script>
</body>
</html>
如上，比较简单