关于document.referrer
首页
<html><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head>
<frameset rows="*" cols="100%" framespacing="0" frameborder="NO" border="0">
<frame src="index.htm" name="test">
</frameset>
</html>
index.htm
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>无标题文档</title>
</head>
<body >
<form name="form1" method="post" action="" >
<input name="btnLogin" type="button" value=" 登录 " onclick="test()">
</form>
<script language="javascript" >
function test()
{
var str=document.referrer;
alert(str);
}
</script>
</body>
</html>
为什么在index.htm页面document.referrer为空