You can customize the content of the TreeView nodes using the formatItem event. The event handler parameters include the element that represents the node and the data item being rendered.

The example below uses the formatItem event to add a "new" badge to the right of new items on the tree.

Electronics

Trimmers/Shavers

Tablets

Phones

Apple

Motorola

Nokia

Samsung

Speakers

Monitors

Toys

Shopkins

Train Sets

Science Kit

Play-Doh

Crayola

Home

Coffeee Maker

Breadmaker

Solar Panel

Work Table

Propane Grill

// This file locates: "Scripts/Lesson/C1Nav/CustomContent.js".
c1.documentReady(function () {
    var tree = wijmo.Control.getControl('#theTree');
 
    tree.formatItem.addHandler(function (s, e) {
        if (e.dataItem.NewItem) {
            var imgUrl = newImageUrl;
            e.element.innerHTML +=
                '<img class="new-icon" src="' + imgUrl + '">';
        }
    });
});

// This file locates: "Content/css/Lesson/C1Nav/CustomContent.css".
.new-icon {
  margin-left: 12px;
  transform: rotate(-30deg);
}
/* default trees on this sample */
.demo-control .wj-treeview {
    display:block;
    height: 350px;
    font-size: 120%;
    margin-bottom: 8px;
    padding: 6px;
    background: #f0f0f0;
    box-shadow: 0 3px 6px rgba(0,0,0,0.16), 0 3px 6px rgba(0,0,0,0.23);
}

using System.Web.Mvc;
 
namespace LearnMvcClient.Controllers
{
    public partial class C1NavController : Controller
    {
        // GET: CustomContent
        public ActionResult CustomContent()
        {
            return View(Models.TreeViewData.GetData(Url));
        }
    }
}

@model IEnumerable<TreeViewData>
 
@section Scripts{
<script>
    var newImageUrl = '@Href("~/Content/images/new.png")';
</script>
}
 
<h1>
    @Html.Raw(Resources.C1Nav.CustomContent_Title)
</h1>
 
<p>
    @Html.Raw(Resources.C1Nav.CustomContent_Text1)
</p>
<p>
    @Html.Raw(Resources.C1Nav.CustomContent_Text2)
</p>
 
@Html.C1().TreeView().Id("theTree").Bind(Model).DisplayMemberPath("Header").ChildItemsPath("Items")