JS判断易优会员是否登陆

<script type="text/javascript">     function layerLogin(gourl) {         if (0 < ey_getCookie('users_id')) {             alert('已经登录');         }else{             alert('请登录！');         }     }     function ey_getCookie(c_name)     {         return getCookie(c_name);     }     function getCookie(c_name)     {         if (document.cookie.length>0)         {             c_start = document.cookie.indexOf(c_name + "=")             if (c_start!=-1)             {                 c_start=c_start + c_name.length+1                 c_end=document.cookie.indexOf(";",c_start)                 if (c_end==-1) c_end=document.cookie.length                 return unescape(document.cookie.substring(c_start,c_end))             }         }         return "";     } </script>