页面还未加载完毕<html>
<head>
<META content="text/html; charset=gb2312" http-equiv=Content-Type>
<script language="JavaScript" type="text/JavaScript" event="onload" for="window">
<!--
alert(document.all.aaa.value);
-->
</script>
</head>
<body leftmargin="0" topmargin="0">
<input type=button name=aaa value="fdsfds">
</body>
</html>
<head>
<META content="text/html; charset=gb2312" http-equiv=Content-Type>
<script language="JavaScript" type="text/JavaScript" event="onload" for="window">
<!--
alert(document.all.aaa.value);
-->
</script>
</head>
<body leftmargin="0" topmargin="0">
<input type=button name=aaa value="fdsfds">
</body>
</html>
<head>
<META content="text/html; charset=gb2312" http-equiv=Content-Type>
</head>
<body leftmargin="0" topmargin="0">
<input type=button name=aaa value="fdsfds">
<script language="JavaScript" type="text/JavaScript">
alert(document.all.aaa.value);
</script>
</body>
</html>
<head>
<META content="text/html; charset=gb2312" http-equiv=Content-Type>
<script language="JavaScript" type="text/JavaScript">
function window.onload()
{alert(document.aaa.value);}
</script>
</head>
<body leftmargin="0" topmargin="0">
<input type=button name=aaa value="fdsfds">
</body>
</html>