JS缺少对象问题
鄙人刚学JS,很多东西都不懂,麻烦大虾看看这个代码那里的问题!
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>test</title>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=gb2312">
<link type="text/css" href="./css/css2"/>
</head>
<body>
<div id="page_container" >
<script type="text/javascript" >
var var_scwidth=window.screen.width;
var var_rate= var_scwidth/1024;
var var_id= document.getElementById("page_container");
var var_newwidth=var_id.style.width*var_rate;
alter(var_newwidth);
</script>
</div>
</body>
</html>
说这一行缺少对象,这是什么原因???