Global variable in Javascript, rerurn wrong value -

i have problem program. had "tempname" variable. global variable. set value in "ktdn" function , value in function "loadmain" has "undefined". please me!! much!!

var tempname; var tempposititon; function ktdn() {     for(var x=0; x < mangnhanvien.length; x++)     {         if(document.getelementbyid("txtuser").value == mangnhanvien[x].user &&             document.getelementbyid("txtpass").value == mangnhanvien[x].pass)         {             tempname = mangnhanvien[x].ten;             tempposititon = mangnhanvien[x].position;             alert(tempname +" "+tempposititon);//debug ==> right value             //alert("dang nhap thanh cong");             window.open("../html/main.html");             window.open('','_self').close();             return true;         }     }     alert("tai khoan dang nhap khong chinh xac"); } function logout() {     window.open("../html/login.html");     window.open('','_self').close(); } function loadmain() {     document.getelementbyid("lbluser").innerhtml = tempname; //==> wrong value,         "undefined"      document.getelementbyid("lblposition").innerhtml = tempposititon;     var s = "<label for='lstnv'>tìm kiếm:</label><input list='lstnv'><datalist id='lstnv'>";     for( x in mangnhanvien)     {         s += "<option value='"+mangnhanvien[x].ten+"'></option>";     }     s += "</datalist>";     document.getelementbyid("timnv").innerhtml = s;     var tbl = "<table><tr><th>stt</th><th>hỌ tÊn</th><th>giỚi tÍnh</th><th>ngÀy sinh</th><th>cmnd</th><th>ĐỊa chỈ</th><th>sỐ ĐiỆn thoẠi</th><th>ngÀy vÀo lÀm</th><th>ngÀy nghỈ</th></tr>"     for( x in mangnhanvien)     {         tbl += "<tr><td>"+mangnhanvien[x].maso+"</td><td>"+mangnhanvien[x].ten+"</td><td>"+mangnhanvien[x].gioitinh+"</td><td>"+mangnhanvien[x].ngaysinh+"</td><td>"+mangnhanvien[x].cmnd+"</td><td>"+mangnhanvien[x].diachi+"</td><td>"+mangnhanvien[x].sdt+"</td><td>"+mangnhanvien[x].ngayvaolam+"</td><td>"+mangnhanvien[x].ngaynghi+"</td></tr>";     }     tbl += "</table>";     document.getelementbyid("tblnv").innerhtml = tbl; } 

you need make sure ktdn function must called before use global variable value in loadmain function.

also use default value tempname like:

var tempname = 'default value';