Writing a java script on Selecting a CheckBox in ItemTemplate of a DataGrid

Suppose You have a Item Template Of A DataGrid Like This
With HeaderTemplate as asp:CheckBox id="AllSelected" OnClick="javascrip:CheckAll(this,'chk_selected');" runat="server" and ItemTemplate as asp:CheckBox id="chk_selected" OnClick="javascript:CheckChanged('chk_selected','AllSelected');" runat="server"

Then this Javascript Function Will Be Used To Check all the CheckBox of Grid

function CheckAll( checkAllBox,names )
{
//alert(checkAllBox) ;
var frm = document.Form1;
var ChkState=checkAllBox.checked;
for(i=0;i<>
{
e=document.Form1.elements[i];
//alert(document.Form1.elements[i].type) ;
if(document.Form1.elements[i].type=='checkbox' && document.Form1.elements[i].name.indexOf(names) != -1)
{
//alert(document.Form1.elements[i].disabled);
if (document.Form1.elements[i].disabled)
{ //alert("Disabled"); }
else
{ document.Form1.elements[i].checked= checkAllBox.checked ;
} //alert("A");
}
}
}


This Function will be used to Check a Specific CheckBox and UnCheck the Header CheckBox

function CheckChanged(vmycheckbox,vcheckAll) { //alert("Hi"); var frm = document.Form1; var boolAllChecked; boolAllChecked=true; for(i=0;i< e="document.Form1.elements[i];" type="=" checked="=" boolallchecked="false;" i="0;i<" e="document.Form1.elements[i];" type="=" boolallchecked="=" checked=" false" checked=" true;">