Ajax在ASP.NET MVC中上传

HomeController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace ajaxUpload.Controllers
{
    public class HomeController : Controller
    {
        [HttpPost]
        public JsonResult Upload()
        {
            var uploadedFile = Request.Files[0] as HttpPostedFileBase;
            return Json(uploadedFile.FileName);
        }

        public ActionResult Index()
        {
            return View();
        }

    }
}

Index.cshtml@   

ViewBag.Title = "Home Page"}

<div class="jumbotron">
    <h1>Ajax在ASP.NET MVC中上传</h1>
</div>
<div class="row">
    <div id="main">
        <h1>上传您的图片</h1>
        <form id="uploadfrm" method="post" enctype="multipart/form-data" action="/home/upload">
            <input type="file" name="images" id="images" />
        </form>
        <div id="response"></div>
        <ul id="image-list"></ul>
    </div>
    <button onclick="Upload();">上传</button>
</div>

<script>
    function Upload() {
        var form = document.getElementById('uploadfrm');
        var formData = new FormData(form);   // 这里如何把form的数据上传

        $.ajax({ 
            url: "/home/upload",
            type: "POST",
            data: formData,
            processData: false,
            contentType: false,
            success: function (res) {
                document.getElementById("response").innerHTML = res;
            }
        });
    }
</script>