Show (Display) second level on hover of first level using jQuery in ASP.Net

Hello,

I have this jQuery Ajax call which shows first level menu, on hover of any first level category i want to show second level category but its giving error, i think it's not fetching the first level category id on hover.

<script type="text/javascript">
    $(document).ready(function () {
        if (document.title == "Home") {
            // Call your jQuery function here
            loadMoreData();
        }
    });

    $("#acategorybtnmenu").mouseenter(function () {
        loadMoreData();
    }).mouseleave(function () {
        $("#dvfirstlevelcategory").empty(); // unload data by emptying the container element
    });

    function loadMoreData() {
        $.ajax({
            type: "POST",
            url: "/WebMethods/GH_WebMethods.asmx/Category_FirsLevel",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (data) {
                var itemsHtml = "";
                $.each(data.d, function (index, item) {
                    ///FORMATED LIST VIEW
                    itemsHtml += '<div class="first-level-li">';
                    itemsHtml += '<a class="first-level-a" href="/' + item.urlpath + '/category">';
                    itemsHtml += '<span class="first-level-icon">';
                    itemsHtml += '<img src="' + item.icon + '" />';
                    itemsHtml += '</span>';
                    itemsHtml += item.category_name;
                    itemsHtml += '</a>';
                    itemsHtml += '</div>';
                });

                $('[id*=dvfirstlevelcategory]').append(itemsHtml);

                // Add event listeners for the mouseenter event on each first level category element
                $('[id*=dvfirstlevelcategory] .first-level-li').on('mouseenter', function () {
                    var categoryId = $(this).find('.first-level-a').data('category-id');
                    loadSecondLevelData(categoryId);
                });
            },
            error: function (response) {
                alert(response.responseText);
            }
        });
    }

    function loadSecondLevelData(categoryId) {
        $.ajax({
            type: "POST",
            url: "/WebMethods/GH_WebMethods.asmx/Category_SecondLevel",
            data: '{categoryId: "' + categoryId + '" }',
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (data) {
                var itemsHtml = "";
                $.each(data.d, function (index, item) {
                    itemsHtml += '<div class="second-level-li">';
                    itemsHtml += '<a class="second-level-a" href="/' + item.urlpath + '/category">';
                    itemsHtml += '<span class="second-level-icon">';
                    itemsHtml += '<img src="' + item.icon + '" />';
                    itemsHtml += '</span>';
                    itemsHtml += item.category_name;
                    itemsHtml += '</a>';
                    itemsHtml += '</div>';
                });

                var container = $('#dvsecondlevelcategory_' + categoryId);
                container.empty().append(itemsHtml);
                container.show();
            },
            error: function (response) {
                alert(response.responseText);
            }
        });
    }
</script>
<div id="dvfirstlevelcategory" class="first-level-ul"></div>

[WebMethod(EnableSession = true)]
public List<object> Category_FirsLevel()
{
    Entities db = new Entities();
    var q = (from cm in db.category_master
                where cm.IsPublished == true && cm.parent_category_id == 0
                select new
                {
                    category_id = cm.category_id,
                    urlpath = cm.URLPath + "-" + cm.category_id,
                    icon = cm.Icon,
                    category_name = cm.category_name
                });

    return q.OrderBy(u => u.category_name).ToList<object>();
}

[WebMethod(EnableSession = true)]
public List<object> Category_SecondLevel(int categoryid)
{
    Entities db = new Entities();
    var q = (from cm in db.category_master
                where cm.IsPublished == true && cm.parent_category_id == categoryid
                select new
                {
                    category_id = cm.category_id,
                    urlpath = cm.URLPath + "-" + cm.category_id,
                    icon = cm.Icon,
                    category_name = cm.category_name
                });

    return q.OrderBy(u => u.category_name).ToList<object>();
}