How to submit a form via ajax if enctype='multipart/form-data' is used?

Question

JavaScript

I have a form. If you send it without Ajax, everything works fine. But when working through ajax, yii2 returns me an error:

PHP Fatal Error 'yii\base\ErrorException' with message 'Call to a member function saveAs() on a non-object

I think it's because I'm using enctype = 'multipart/form-data' .
Here is the js code:

$('#user-file').on('submit', function(e){
  e.preventDefault();
  var url = $('#user-file').attr('action');
    var data = $('#user-file').serialize();

    $.ajax({
    	type: "POST",
      	url: url,
      	data: data,
    });   
});

How can I make the form work through ajax?

Answer 1

$.ajax({
      url: url,
      type: 'POST',
      data: new FormData( this ),
      processData: false,
      contentType: false,
      success:function(src) {
         //делаем что-то
      }
    });

Answer 2

jquery.form plugin - it works with multipart forms