<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>计算元素样式</title>
    <style type="text/css">
        #myDiv
        {
            background-color: blue;
            width: 100px;
            height: 200px;
        }
    </style>
</head>
<body>
    <div id="myDiv" style="background-color: red; border: 1px solid black">
    </div>

    <script type="text/javascript">

        var myDiv = document.getElementById("myDiv");
        alert(getStyle(myDiv,"backgroundColor"));//"red" 或 rgb(255,0,0)
        alert(getStyle(myDiv,"width")); //"100px"
        alert(getStyle(myDiv,"height")); //"200px"
        alert(getStyle(myDiv,"border"));  //在某些浏览器中是“1px solid black”
        //var computedStyle = document.defaultView.getComputedStyle(myDiv, null);
        //alert(computedStyle.backgroundColor); //"red"
        //alert(computedStyle.width); //"100px"
        //alert(computedStyle.height); //"200px"
        //alert(computedStyle.border); //在某些浏览器中是“1px solid black”
        
        //获取DOM的style属性
        function getStyle(obj,attr)
        {
            if(obj.currentStyle)  //用于IE
            {
                return obj.currentStyle[attr];
            }
            else
            {
                // document.defaultView.getComputedStyle 该方法时DOM2中才出现的方法
                return document.defaultView.getComputedStyle(myDiv, null)[attr];
                //getComputedStyle DOM1中的方法
                //return getComputedStyle(obj,false)[attr];
            }
        }

    </script>

</body>
</html>