js兼容多浏览器添加收藏代码

js兼容多浏览器添加收藏代码
*/

function addfavor(a){
 var url = window.location;
 var title = document.title;
 var ua = navigator.useragent.tolowercase();
 if(ua.indexof("msie 8")>-1){
  external.addtofavoritesbar(url,title,'aa');//ie8
  }else{
   try {
    window.external.addfavorite(url, title);
   } catch(e) {
   try {
   window.sidebar.addpanel(title, url, "");//firefox
   } catch(e) {
    alert("加入收藏失败，请使用ctrl+d进行添加");
   }
  }
 }
 if(login_nid>0){
  if(a!=null && a>0){
   window.open('/collect!addhouse.action?id='+this_htid);
  }else{
   window.open('/collect!addloupan.action?id='+this_bid);
  }
 }
 return false;
}