<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus®">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<title>Document</title>
<style>
.button {
height: 1em;
border: 0;
border-radius: .2em;
background-color: #34538b;
color: #fff;
font-size: 12px;
font-weight: bold;
}
</style>
</head>
<body>
<input type="button" id="button" class="button" value="点击我，显示高度" />
<script>
document.getElementById("button").onclick = function() {
//var oStyle = this.currentStyle? this.currentStyle : window.getComputedStyle(this, null);
var oStyle = this.currentStyle || window.getComputedStyle(this, null);//IE下获取是2em,Firefox下获取的是24px;浏览器默认1em=16px;
alert(oStyle.height);
};
</script>
</body>
</html>
getComputedStyle获取css属性与IE下的currentStyle获取到的值不同
原文：http://www.cnblogs.com/double405/p/4592796.html