submit a file or form with iframe in javascript

 $('#ad6 #uploaddatabtn').click(function(){
  console.dir('------EthanYen M9505506@gmail.com------')
   var iframe = $('');
            $("body").append(iframe);
            var form = $('#formSend2');
            form.attr("action", "./api/contentInput2.php");
            form.attr("method", "POST");
            form.attr("encoding", "multipart/form-data");
            form.attr("enctype", "multipart/form-data");
            form.attr("target", "tempIframe");
            //form.attr("file", $('#userfile').val());
            form.submit();
            $("#tempIframe").load(function () {
                iframeContents = this.contentWindow.document.body.innerHTML;
                console.dir(iframeContents)
                $(iframe).remove()
                $("#textarea").html(iframeContents);
            });
            //return false;
 })