I Don\'t understand that... call its always undefined
Create the mock file:
var mockFile = { name: \"Filename\", size: 12345 };
You can also do with the following code:
EDIT
Since update of Dropzone 4.0 init function can be called as:
init: function () {
var mockFile = { name: "myimage.jpg", size: 12345, type: 'image/jpeg' };
this.options.addedfile.call(this, mockFile);
this.options.thumbnail.call(this, mockFile, "http://someserver.com/myimage.jpg");
mockFile.previewElement.classList.add('dz-success');
mockFile.previewElement.classList.add('dz-complete');
}