js實作網頁防止被iframe框架嵌套及幾種location.href的區別

首先我們了解：window.location.href、location.href、self.location.href、parent.location.href、top.location.href他們的區別與聯繫，簡單的說：幾種location.href的區別js實作網頁被iframe框架功能 
"window.location.href"、"location.href"、"self.location.href"是本頁跳轉 
"parent.location.href"是上一層頁跳到 
"top.location.href"是最外層的頁面跳轉 

舉個例子說明（如上圖）： 
如果A,B,C,D都是普通頁面，D是C的iframe，C是B的iframe，B是A的iframe， 
如果D中js這樣寫： 
"window.location.href"、"location.href"：D頁跳到 
"parent.location.href"：C頁跳轉 
" top.location.href"：A頁跳轉 

如果D頁有form的話： 

<script language="javascript"> 
if(top.location!==self.location){ 
WarningTxt1 = "content页面被iframe了！"; 
WarningTxt2 = "我们跳出iframe，直接访问content页面吧！"; 
alert(WarningTxt1); 
alert(WarningTxt2); 
top.location.href=self.location.href; 
} 
</script>