用javascript获得div的位置

<div class="l" id="left"><img src="images/meis.png" /></div>用js取这个div的位置：document.getElementById("left").style.marginLeft，用alert打印时获得的margin-lefg值为空
但是我的css里面定义的.l{margin-left:10px;}，这是为什么？

解决方案 »

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<div class="l" id="left"><img src="images/meis.png" style="margin-left:10px;"/></div>
因为javascript不能获取到页面上没有的属性
currentStyle.marginLeft试下。
css：.l{
margin-left:10px;
margin-top:50px;
float:left;
width:154px;
height:210px;
}
html：<html><script language= "javascript" type="text/javascript">
var VK_LEFT = 37;
var VK_RIGHT = 39;
document.onkeydown = function handelKey(e){
e = e||window.event;
var keyCode = e.keyCode||e.which;
switch(keyCode){
case VK_LEFT:
keyLeft();
break;
case VK_RIGHT:
keyRight();
break;
default:
    break;
}
}
function keyLeft(){
alert("left");
}
function keyRight(){
alert(document.getElementById("left").style.marginLeft);
}</script>
                </head>
                    <body >
                     <div class="l" id="left"><img src="images/meis.png" /></div>
                    </body>
              </html>按右键的时候弹出的对话框是空白的
<html>
<script language= "javascript" type="text/javascript">
    var VK_LEFT = 37;
    var VK_RIGHT = 39;
    document.onkeydown = function handelKey(e){
        e = e||window.event;
        var keyCode = e.keyCode||e.which;
        switch(keyCode){
        case VK_LEFT:
            keyLeft();
            break;
        case VK_RIGHT:
            keyRight();
            break;
        default:
            break;
        }
        }
    function keyLeft(){
        alert("left");
        }
    function keyRight(){
        alert(document.getElementById("left").style.marginLeft);
        }</script>
</head>
<body >
<div class="l" id="left" style="margin-left:10px;"><img src="images/meis.png" /></div>
</body>
</html>