MultiHandleSliderExtender and postback javascript issues

Question

I am trying t use the multihandlesliderextender (from the Ajax Toolkit) to make a filter option on the price in a webshop. When a new price is selected, it has to reload everything (and do a lot of behind the scenes code).

I've used this article here http://forums.asp.net/p/1397694/3022998.aspx as inspiration, and the primary idea is to use JavaScript to make the postback.

I have the following error when running my page: "Microsoft JScript runtime error: Unable to set value of the property 'Handle': object is null or undefined" .

I guess it's because the JavaScript can't find the control, but I don't get why it doens't work as I use ClientIdMode to make sure ID should match (and looking in the generated HTML it should work).

Thanks!

I've the following markup:

 <asp:TextBox ID="txtSlider" runat="server" AutoPostBack="true" ></asp:TextBox>
        <asp:MultiHandleSliderExtender ID="MultiHandleSliderExtender1" BehaviorID="MultiHandleSliderExtender1"
            runat="server" TargetControlID="txtSlider" Length="120" TooltipText="{0}" OnClientDragEnd="ValueChangedHandler">
        <MultiHandleSliderTargets>
                <asp:MultiHandleSliderTarget ControlID="LeftHandle" />
<asp:MultiHandleSliderTarget ControlID="RightHandle" />

            </MultiHandleSliderTargets>

        </asp:MultiHandleSliderExtender>

        <br/><br/>
            <asp:TextBox ID="LeftHandle" runat="server" ClientIDMode="Static"></asp:TextBox>
            <asp:HiddenField ID="HiddenField1" runat="server" ClientIDMode="Static" />


<asp:Label ID="RightHandle" runat="server" ClientIDMode="Static"></asp:Label>
 <asp:HiddenField ID="HiddenField2" runat="server" ClientIDMode="Static" />


        <asp:Button ID="Button1" runat="server" Text="Button" 
    Style="display: none" onclick="Button1_Click" />
        <asp:Label ID="Label1" runat="server" Text=""></asp:Label>

And in my header the following JavaScript:

 <script type="text/javascript">

     function ValueChangedHandler(sender, args) {
         $get("HiddenField1").value = $get("LeftHandle").value;
         $get("HiddenField2").value = $get("RightHandle").value;
         __doPostBack("Button1", "Click");
     }

</script>

Answer 1

I solved this by updating in the page_load event instead, like this:

var controlId = Request.Form["__EVENTTARGET"];
            var control = Page.FindControl(controlId);

            if(control.ID == sliderTwo.ID)
            {
                SetupPriceFilter(p);
            }
            else if (control.ID == sliderAge.ID)
            {
                SetupAgeFilter( p);
            }