js提取cookie异常

function count(){
    var tmp="";
    var d=new Date();
    d.setMonth(d.getMonth()+6);
    var co=document.cookie.split(";");
    for(var i=0;i<co.length;i++){
    //alert(co[i].split("=")[0]);
    tmp=co[i].split("=")[0];
    alert(tmp);
    if(tmp=="count"){
        alert("XX");
        document.getElementById("count").innerHTML="访客人数:"+co[i].split("=")[1];
        co[i].split("=")[1]=Number(co[i].split("=")[1])+1;
        return false;
    }
    }
    //document.cookie="info="+info+";expires="+d.toUTCString();
    document.cookie="count=0;expires="+d.toUTCString();
    document.getElementById("count").innerHTML="您是首次访问者";
}