select all checkboxes using one checkbox in datalist - asp.net

Question

this is my code when i click on checkbox chkall , all checkboxes should be activated.
so can please anyone help me
<asp:DataList ID="DataList1" runat="server" OnItemCommand="DataList1_ItemCommand" CellPadding="4" ForeColor="#333333">
<FooterStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<HeaderStyle BackColor="#507CD1" Font-Bold="True" ForeColor="White" />
<HeaderTemplate>
<asp:CheckBox ID="chkall" runat="server" onclick="checktrue()" />
EMPID ENAME DESIGNATION DOJ SALARY DEPTNO Edit/Update
</HeaderTemplate>
<ItemStyle BackColor="#EFF3FB" />
<ItemTemplate>
<asp:CheckBox ID="chkone" runat="server" />
<asp:Label ID="lblempid" runat="server" Text='<%#Eval("empid") %>' />
<%#Eval("ename") %>
<%#Eval("desg") %>
<%#Eval("doj") %>
<%#Eval("salary") %>
<%#Eval("deptno") %>
<asp:Button ID="btnedit" runat="server" Text="EDIT" CommandName="Edit" />
</ItemTemplate>
<AlternatingItemStyle BackColor="White" />
<EditItemTemplate>
<asp:Label ID="lblempid" runat="server" Text='<%#Eval("empid") %>' />
<asp:TextBox ID="txtename" runat="server" Text='<%#Eval("ename") %>' />
<asp:TextBox ID="txtdesg" runat="server" Text='<%#Eval("desg") %>' />
<asp:TextBox ID="txtdoj" runat="server" Text='<%#Eval("doj") %>' />
<asp:TextBox ID="txtsalary" runat="server" Text='<%#Eval("salary") %>' />
<asp:TextBox ID="txtdeptno" runat="server" Text='<%#Eval("deptno") %>' />
<asp:Button ID="btnupdate" runat="server" Text="Update" CommandName="Update" />
<asp:Button ID="btncancel" runat="server" Text="Cancel" CommandName="Cancel" />
</EditItemTemplate>
<FooterTemplate>
<asp:Button ID="btmdelete" runat="server" OnClick="btndelete_Click" Text="Delete" />
<asp:TextBox ID="txtempid" runat="server" Width="60"></asp:TextBox>
<asp:TextBox ID="txtename" runat="server" Width="60"></asp:TextBox>
<asp:TextBox ID="txtdesg" runat="server" Width="60"></asp:TextBox>
<asp:TextBox ID="txtdoj" runat="server" Width="60"></asp:TextBox>
<asp:TextBox ID="txtsalary" runat="server" Width="60"></asp:TextBox>
<asp:TextBox ID="txtdeptno" runat="server" Width="60"></asp:TextBox>
<asp:Button ID="btnadd" runat="server" Text="add" CommandArgument="add" />
</FooterTemplate>
<SelectedItemStyle BackColor="#D1DDF1" Font-Bold="True" ForeColor="#333333" />
</asp:DataList>

Answer 1

I recommend doing it on the client side. Here is an example with jquery
function checkAll(){
$("#DataList1 :checkbox").prop("checked", $("#chkall").prop("checked"));
}