1、obj.currentStyle.styleName 只兼容IE
2、getComputedStyle(obj, false).styleName 不兼容IE8
于是有了兼容性写法：
function getStyle(obj, sName){
return (obj.currentStyle || getComputedStyle(obj, false))[sName];
}
demo：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>DEMO - Lik</title>
<style>
div{
width:100px;
height:200px;
background:blue;
}
</style>
</head>
<body>
<div></div>
<script>
function getStyle(obj, sName){
return (obj.currentStyle || getComputedStyle(obj, false))[sName];
}
var oDiv = document.getElementsByTagName('div')[0];
console.log(getStyle(oDiv, 'width')); // 100px
console.log(getStyle(oDiv, 'height')); // 200px
console.log(getStyle(oDiv, 'background')); // rgb(0, 0, 255) none repeat scroll 0% 0% / auto padding-box border-box
</script>
</body>
</html>