Check the MIME type of file before upload it

<div class="col-lg-8 control-section">
    <div class="control_wrapper">
        @Html.EJS().Uploader("UploadFiles").Uploading("onBeforeUpload").AutoUpload(false).DropArea(".control-fluid").AsyncSettings(new Syncfusion.EJ2.Inputs.UploaderAsyncSettings { SaveUrl = "https://aspnetmvc.syncfusion.com/services/api/uploadbox/Save", RemoveUrl = "https://aspnetmvc.syncfusion.com/services/api/uploadbox/Remove" }).Render()
    </div>
</div>

<script>

    function onBeforeUpload(args) {
        // get the file MIME type
        alert("File MIME type is: " + args.fileData.rawFile.type);
    }

</script>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;

namespace EJ2CoreSampleBrowser.Controllers.TextBoxes
{
    public partial class UploaderController : Controller
    {
        public ActionResult DefaultFunctionalities()
        {
            
            return View();
        }
    }
}

.control_wrapper {
        max-width: 500px;
        margin: auto;
    }

    .control_wrapper .e-upload .e-upload-drag-hover {
        margin: 0;
    }