为什么我用getElementById得到的对象属性为空呢？
<body><img src="../javascript/images/icon2.gif" id="img2" /><script type="text/javascript"> var ml = document.getElementById("img2"); alert(ml.style.height);</script></body><body><img src="../javascript/images/icon2.gif" id="img2" style="height:10px" /><script type="text/javascript"> var ml = document.getElementById("img2"); alert(ml.style.height);</script></body>