看不到alert出的结果
OCTYPE html>
<html>
<head>
<title></title>
<style type="text/css">
body{
margin: 0;
padding: 0;
position: relative;
}
.bb{
width: 200px;
height: 200px;
background: red;
position: absolute;
left: 100px;
color:#fff;
}
</style>
</head>
<body>
<div class="bb"></div>
<script type="text/javascript">
var divE = document.getElementsByTagName('div')[0];
divE.style.background="#ec6";
var mm = divE.style.left;
alert(mm);
</script>
</body>
