<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style>
#dakuang {
width: 1000px;
height: 30px;
}
#left,
#right {
height: 100%;
float: left;
}
#left {
background-color: red;
/*width: 335px;*/
}
#right {
background-color: cadetblue;
/* width: 165px;*/
}
</style>
</head>
<body>
<div id="dakuang">
<div id="left"></div>
<div id="right"></div>
</div>
<input type="button" value="岳钱" id="btn1" />
<input type="button" value="李强" id="btn2" />
<script>
var left, right, btn1, btn2;
var result = 500;
var r1 = 335;
window.onload = function() {
left = document.getElementById("left");
right = document.getElementById("right");
btn1 = document.getElementById("btn1");
btn2 = document.getElementById("btn2");
btn1.onclick = function() {
result++;
r1++;
suan();
}
btn2.onclick = function() {
result++;
suan();
}
suan();
function suan() {
var b1 = r1 / result;
var num1 = Math.round(b1 * 100);
left.innerHTML = "0." + num1;
right.innerHTML = "0." + (100 - num1);
var div = document.getElementById("dakuang");
// 获取大div的宽度
var width = div.offsetWidth;
// 把div左的宽度算出来
var leftWidth = width * b1;
left.style.width = leftWidth * b1 + "px";
right.style.width = (width - leftWidth) + "px";
}
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/cxy66/p/6050336.html