Pass Id parameter into ajax function

AJAX function is not passing Id parameter to GET method in my controller.

I have this table.

 @foreach (var user in Model)
                {
                    <tr>
                        <td>@user.FirstName</td>
                        <td>@user.LastName</td>
                        <td>@user.Email</td>
                        <td>@string.Join(" , ", user.Roles.ToList())</td>
                        <td>
                            <a class="btn btn-primary" onclick="manageRolePopup('@Url.Action("Manage","Role",                                     new {id=user.UserId },Context.Request.Scheme)')">Manage Roles</a>

                            <partial name="_RoleManagePopup.cshtml" />
                        </td>
                    </tr>
                }

On click I want to show in popup user first name and last name so I have this in my Controller

 [HttpGet]
        public async Task<IActionResult> Manage(string userId)
        {
            var user = await _userManager.FindByIdAsync(userId);

            ViewBag.FirstName = user.FirstName;
            ViewBag.LastName = user.LastName;

            var model = new ManageRoleViewModel();

            List<string> roleNames = new List<string>();

            foreach(var role in _roleManager.Roles)
            {
                model.RoleId = role.Id;
                roleNames.Add(role.Name);
            }
            model.UserId = user.Id;
            model.RoleNames = roleNames;

            return View(model);
        }

AJAX

manageRolePopup = (url) => {
    $.ajax({
        type: "GET",
        url: url,
        success: function (res) {
            $("#form-modal .modal-body").html(res);
            $("#form-modal").modal("show");
        }
    })
}

View

<form method="post" asp-controller="Role" asp-action="Manage" asp-route-UserId="@Model.UserId">
    <div class="row">
        <div class="col-3">
            <h4>@ViewBag.FirstName @ViewBag.LastName</h4>

            <div class="form-group">
                <select asp-items="@new SelectList(Model.RoleNames)">
                    <option selected disabled>---Select New Role---</option>
                </select>
            </div>
        </div>
    </div>
</form>

When im passing Id like below, everything is good. User is not null, Id parameter also.

<a asp-controller="Role" asp-action="Manage" asp-route-UserId="user.UserId"></a>

Obviously I want to do UPDATE method but for now I just want to have it displayed.

>Solution :

you have to add userId to your ajax url

var userId=$("#userId").val();
 $.ajax({
        type: "GET",
        url: url+"?UserId="+userId,
        ....

to get userId you have to add it as hidden field

  <td> <input type="hidden" value="@user.UserId" id="userId" /> </td>