HTML5 file upload formdata with jquery ajax

I want to use html5 formData along with jquery ajax to perform ajax file upload (Single File), but this not working. Below is my js code

//I tried this but return Cannot read property '0' of undefined
  var file = $folderID.find('.add-file').files[0];  

//I also tried this no error return, no file uploaded, no data inserted to db.
var file = $folderID.find('.add-file')[0].files[0];
  var formData = new FormData();
  formData.append("file", file);

var tag = $folderID.find('.hidden-tag').val();

$.ajax({
    type: 'POST',
    contentType:false,
    processData:false,
    url: baseUrl + 'folder/post',
    data: {'file':formData ,'tag':tag},
    error: function (request, status, error) {
        alert(request.responseText);
      }
  });

Note: the php file is working perfectly without using ajax.

Update headers return 302 not found and request payload [object] [object]