Autorefresh DropDownJS

I'm trying to use dropdown js to load an image, but when I drag and drop that image, the page automatically reloads the data I had included in the form, what can I do there?

This is the page of the library link

and I'm trying to implement it in C # .Net

HTML

'

<form id="dropZoneForm" action="@Url.Action("FileUpload", "Campaign")" class="dropzone col-md-3">
    @Html.AntiForgeryToken()
    <div class="fallback">
        <input name="file" type="file" multiple />
    </div>
</form>

'

Driver '

[HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult FileUpload()
        {
            bool isSavedSuccessfully = true;
            string fName = "";
            try
            {
                foreach (string fileName in Request.Files)
                {
                    HttpPostedFileBase file = Request.Files[fileName];
                    fName = string.Concat(Guid.NewGuid().ToString(), Path.GetExtension(file.FileName));
                    if (file != null && file.ContentLength > 0)
                    {
                        var originalDirectory = new DirectoryInfo(string.Format("{0}CampaignImages\", Server.MapPath(@"~\Uploads\")));
                        string pathString = System.IO.Path.Combine(originalDirectory.ToString(), "tempimagepath");
                        bool isExists = System.IO.Directory.Exists(pathString);
                        if (!isExists)
                            System.IO.Directory.CreateDirectory(pathString);
                        var path = string.Format("{0}\{1}", pathString, fName);
                        file.SaveAs(path);
                    }
                }
            }
            catch (Exception ex)
            {
                isSavedSuccessfully = false;
            }
            if (isSavedSuccessfully)
            {
                return Json(new { Message = fName });
            }
            else
            {
                return Json(new { Message = "Error in saving file" });
            }
        }

'

Javascript '

Dropzone.options.dropZoneForm = {
            acceptedFiles: 'image/*',
            maxFiles: 1,
            addRemoveLinks: false,  
            dictRemoveFile: 'Eliminar',
            parallelUploads: 1,
            dictMaxFilesExceeded: 'Solo se puede cargar 1 elemento.',
            init: function () {
                this.on("maxfilesexceeded", function (file) {
                    this.removeAllFiles();
                    this.addFile(file);
                    //En caso de exceder el limite, queda sin clickearse
                    dropZoneForm.clickable = false
                });
                this.on("addedfile", function (file) {
                    //Elimina la primera imagén cargada, cada vez que se agrega una segunda
                    if (this.files.length > 1) {
                        this.removeFile(this.files[0]);
                    }
                });
                this.on("complete", function (file) {
                    //Los var, son para evitar errores de undefined
                    var xhr = new XMLHttpRequest();
                    var data = file.xhr.responseText;
                    var jsonResponse = JSON.parse(data);
                    $('#Imagen').val(jsonResponse['Message']);
                });
            }
        };

'