easyui表单提交文件

<form id="form1" method="post" enctype="multipart/form-data">
    <fieldset>
        <legend>用Ajax把Form表单提交到远程服务器Api</legend>
        <div class="form-group">
            <label class="col-sm-6 control-label" for="ds_host">选择文件</label>
            <div class="col-sm-4">
                <input type="file" name="file" id="inpFile" dirname="inpFile" />
            </div>
            <div class="col-sm-2">
                <input type="button" value="提交" id="inpUpload" />
            </div>
        </div>
    </fieldset>
    <script src="/plugins/jquery-3.3.1.min.js"></script>
    <script src="/plugins/easyui/jquery.easyui.min.js"></script>
    <script>
        $(document).ready(function () {
            $("#inpUpload").click(function () {
                var fileObj = $("#inpFile").get(0).files[0];
                if (fileObj == null) {
                    alert("请选择要上传的文件");
                    return false;
                }
                $("#form1").form("submit", {
                    url: "http://localhost:19501/Files/ReceiveFileTest",
                    onSubmit: function (params) {
                        //提交前检查
                        return true;
                    },
                    success: function (data) {
                        console.log(data);
                        var data = eval('(' + data + ')');
                        alert(JSON.stringify(data));
                    }
                });
            });
        });
    </script>
</form>