checkbox全选取消

function CheckAll(chkAllBox)
    {
        if(chkAllBox.checked==true)
            chkAllBox.title="取消"
        else
            chkAllBox.title="全选"
        for(var i=2;i<100;i++)
       {
            var chkID = "";
            if(i<10)
            {
                chkID = "0" + i;
            }
            else
                chkID = i;
            chkID = "GridView1_ctl" + chkID + "_chk";
            if(document.getElementById(chkID) != null)
                document.getElementById(chkID).checked = chkAllBox.checked;
        }
     }