Filtering - C1 ASP.NET MVC

// This file locates: "Scripts/Lesson/C1FlexGrid/Filtering.js".
c1.documentReady(function () {
    var theGrid = wijmo.Control.getControl('#theGrid');
 
    document.getElementById('filter').addEventListener('input', function (e) {
        var filter = e.target.value.toLowerCase();
        theGrid.collectionView.filter = function (item) {
            return filter.length == 0 || item.Country.toLowerCase().indexOf(filter) > -1
        }
    });
});

using System.Web.Mvc;
 
namespace LearnMvcClient.Controllers
{
    public partial class C1FlexGridController : Controller
    {
        // GET: Filtering
        public ActionResult Filtering()
        {
            return View(Models.FlexGridData.GetSales(200));
        }
    }
}

@model IEnumerable<FlexGridData.Sale>
 
<h1>
    @Html.Raw(Resources.C1FlexGrid.Filtering_Title)
</h1>
<p>
    @Html.Raw(Resources.C1FlexGrid.Filtering_Text1)
</p>
<p>
    @Html.Raw(Resources.C1FlexGrid.Filtering_Text2)
</p>
<div class="input-group">
    <div class="input-group-addon"><span class="glyphicon glyphicon-search"></span></div>
    <input id="filter" class="form-control" placeholder="@Resources.C1FlexGrid.Filtering_Text3">
</div>
@Html.C1().FlexGrid().Id("theGrid").Bind(b=>b.Bind(Model).DisableServerRead(true)).Height(250)