ajax请求发送文件

I have a jQuery exception

"Uncaught TypeError: Illegal invocation" in line "data: formData",

when I try to send the next request:

$("#loader").on("change", function (data) {                      

            var formData = new FormData($('form')[0]);
            $.ajax({
                url: "/Admin/SaveImage",
                type: "post",
                data: formData,                
                success: function (path) {

                    if (path.value != "") {
                        $("#picture").attr("src", path.value);
                        $("#loader").val(null);
                    }
                }
            });            
        });

$("#loader").on("change", function () {

        if (this.files && this.files[0]) {

            var reader = new FileReader();
            reader.onload = function (e) {

                $("#picture").attr("src", e.target.result);
            }
            reader.readAsDataURL(this.files[0]);
        }
    });