javaScript checkbox Select all/reselect and batch deletion

<script type="text/javascript">
var a;
function CheckAll(){
if(a==1)
{
for(var i=0;i<.;i++)
{
var e = [i];
=false;
}
a=0;
}
else
{
for(var i=0;i<.;i++)
{
var e = [i];
=true;
}
a=1;
}
}
function CheckDel(){
var number=0;
for(var i=0;i<.;i++)
{
var e = [i];
if ( != "CheckBoxAll")
{
if(==true)
{
number=number+1;
}
}
}
if(number==0)
{
alert("Please select the item that needs to be deleted!");
return false;
}
if (("Do you confirm the deletion?"))
{
return true;
}
else
{
return false;
}
}
<asp:LinkButton ID="lbDelete" runat="server" OnClientClick="javascript:return CheckDel();" onclick="lbDelete_Click">
<img alt="" src="../images/" width="16" height="16" border="0" /> Delete </asp:LinkButton>
<input type="checkbox" onclick="CheckAll()" />
<input name="MenuID" type="checkbox" value="<%#Eval("Menu_ID") %>" />