1 <textarea placeholder="填写其它原因" class="notes Font-Min valid" cols="20" data-val="true" data-val-required="填写其它原因内容" id="OtherNotes" name="OtherNotes" rows="2" aria-required="true" aria-describedby="OtherNotes-error" aria-invalid="false">&lrm;&zwnj;</textarea>

 @using (Ajax.BeginForm("CancelOrder", "Admin", new AjaxOptions()))
            {
                @Html.AntiForgeryToken()
                @Html.HiddenFor(m => m.Token)
                @Html.HiddenFor(m => m.Id)
                <div class="fc-ln-tab">
                    <table>
                        <tbody>
                        <tr>
                            <td class="width-60">取消原因</td>
                            <td>@Html.DropDownListFor(m => m.Reason, Model.Reasons, new { @class = "sec",onchange="SelCancelReason(this);" })</td>
                        </tr>
                        </tbody>
                    </table>
                </div>
                <div class="fc-ln-tab">
                    <table>
                        <tbody>
                        <tr>
                            <td class="width-60">其它原因<br />说明</td>
                            <td><textarea placeholder="填写其它原因" class="notes Font-Min valid" cols="20" data-val="true" data-val-required="填写其它原因内容" id="OtherNotes" name="OtherNotes" rows="2" aria-required="true" aria-describedby="OtherNotes-error" aria-invalid="false">&lrm;&zwnj;</textarea></td>
                        </tr>
                        <tr>
                            <td class="width-60"></td>
                            <td class="ms_er error">@Html.ValidationMessageFor(m=>m.OtherNotes)</td>
                        </tr>
                        </tbody>
                    </table>
                </div>
                <div class="fc_sub">
                    <input type="submit" value=http://www.mamicode.com/"申请取消" />
                </div>
            }

function SelCancelReason(it) {
            if ($(it).val() === "") {
                $("#OtherNotes").val("");
            } else {
                $("#OtherNotes").val("\0");
            }
        }

[HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<ActionResult> CancelOrder(CancelOrderVm model)
        {
            if (ModelState.IsValid)
            {
            }
        }