使用JavaScript在代码隐藏中设置的输入值

Question

So I have a repeater that creates <li> elements. This is the codebehind for the OnItemDataBound

var categoryList = (ProductCategoryObject) e.Item.DataItem;
            var category = ((HtmlAnchor) e.Item.FindControl("category"));
            category.HRef = "javascript:void(0);";
            category.InnerText = categoryList.Name;
            category.Attributes.Add("onclick", "javascript:$('#ProductCategory').val('" + categoryList.Id + "');$('button.product-categories span').text('" + categoryList.Name + "');");

This sets the value of an input of type hidden and now my question is how do I get that value on button click? It appears to disappear on postback and I've tried Request["ProductCategory"] and Request.Form["ProductCategory"]

Here is the markup:

<div class="input-group margin-bottom-30">
    <div id="divCategories" runat="server" class="input-group-btn">
        <button type="button" class="btn blue dropdown-toggle  product-categories" data-toggle ="dropdown">
            <asp:Label runat="server" ID="lblCategory">All Categories</asp:Label> <i class="icon-angle-down"></i>
        </button>
        <ul runat="server" ID="ulCategory" class="dropdown-menu">
            <asp:Repeater runat="server" id="rptCategories" OnItemDataBound="CategoriesOnItemDataBound">
                <ItemTemplate>
                    <li>
                        <a runat="server" id="category"></a>
                    </li>
                </ItemTemplate>
            </asp:Repeater>
        </ul>
        <input id="ProductCategory" type="hidden" />
    </div>
    <asp:TextBox runat="server" ID="txtSearch" CssClass="form-control"></asp:TextBox>
    <div class="input-group-btn">
        <asp:LinkButton ID="btnFilter" runat="server" CausesValidation="True" ValidationGroup="BaseValidationGroup" CssClass="btn green" OnClick="SearchBtnOnClick"> Search <i class="icon-search"></i> </asp:LinkButton>
    </div>
</div>

Answer 1

So I figured it out, I had to change my the markup for my input control from

<input id="ProductCategory" type="hidden" />

to

<input id="ProductCategory" name="ProductCategory" type="hidden" />

So, essentially, I was missing the name tag which is needed for Request.Form["ProductCategory"] to work.