更换title上的ico

var rurl = "/static/dashboard/img/favicon.ico"; 
var a = '';
var links = document.getElementsByTagName("link"); 
var link = {}; 
for(var i=0;i<links.length;i++){ 
  link = links[i]; 
    if(link.rel === "shortcut icon"){ 
       link.href = rurl; 
  　　　a = link.href;
       break; 
    }  
} 
alert(a);