页面加载时判断是否登陆（js）

function checklog(){//验证用户是否登录    var search="name=";    begin=document.cookie.indexOf(search);    if(begin!=-1)    {        begin+=search.length;        end=document.cookie.indexOf(";",begin);        if(end==-1)        {            end=document.cookie.length;        }        document.getElementById("pageNameD").innerHTML="<h1>对不起，"+document.cookie.substring(begin,end)+".您已经登录。</h1>"        document.all.pageName.style.display='none'    }else    {        document.all.pageNameD.style.display='none'    }}