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);