Pass a gridview column value to a session using javascript

I have a gridview that contains a list of products. What i am trying to do is using the ItemTemplate is pass the ProductID of the selected item using an Onclick event to a session so i can then lookup that session on another page to avoid having the ProductID shown in the URL.

    <asp:GridView ID="GVProducts" runat="server" 
         onselectedindexchanged="GVProducts_SelectedIndexChanged">
      <Columns>
                 <asp:ImageField DataImageUrlField="FileName"  
                     DataImageUrlFormatString="Images/{0}" HeaderText="Image">
                     <ControlStyle Height="80px" Width="80px" />
             </asp:ImageField>
               <asp:TemplateField HeaderText="Title" SortExpression="ProductID" > 
 <ItemTemplate> 
         <a onclick="javascript:function setSessionVariable(<%#Eval("ProductID")%>)"  href="ProductDetail.aspx"><%#Eval("Title")%></a> 
 </ItemTemplate></asp:TemplateField> 
 
         </Columns>
               <FooterStyle BackColor="#99CCCC" ForeColor="#003399" />
               <HeaderStyle BackColor="#003399" Font-Bold="True" ForeColor="#CCCCFF" />
               <PagerStyle BackColor="#99CCCC" ForeColor="#003399" HorizontalAlign="Left" />
               <RowStyle BackColor="White" ForeColor="#003399" />
               <SelectedRowStyle BackColor="#009999" Font-Bold="True" ForeColor="#CCFF99" />
               <SortedAscendingCellStyle BackColor="#EDF6F6" />
               <SortedAscendingHeaderStyle BackColor="#0D4AC4" />
               <SortedDescendingCellStyle BackColor="#D6DFDF" />
               <SortedDescendingHeaderStyle BackColor="#002876" />
     </asp:GridView>
 

Hopefully it is something simple as i am just starting out with javascript but i cant seem to get it to pass to the session.

Thanks

---