How to invoke an error from server response (JSON) in Dropzone JS?

Dropzone has built in error detection. Just do this:

mydropzone = new Dropzone("#mydropzone",{
    url: "/dropzone",
    addRemoveLinks : true,
    maxFilesize: 2.0,
    maxFiles: 100,
    error: function(file, response) {
        if($.type(response) === "string")
            var message = response; //dropzone sends it's own error messages in string
        else
            var message = response.message;
        file.previewElement.classList.add("dz-error");
        _ref = file.previewElement.querySelectorAll("[data-dz-errormessage]");
        _results = [];
        for (_i = 0, _len = _ref.length; _i < _len; _i++) {
            node = _ref[_i];
            _results.push(node.textContent = message);
        }
        return _results;
    }   
});

okay the following would work, just extract from the source:

success: function(file, response){
  if(response.code == 501){ // succeeded
    return file.previewElement.classList.add("dz-success"); // from source
  }else if (response.code == 403){  //  error
    // below is from the source code too
    var node, _i, _len, _ref, _results;
    var message = response.msg // modify it to your error message
    file.previewElement.classList.add("dz-error");
    _ref = file.previewElement.querySelectorAll("[data-dz-errormessage]");
    _results = [];
    for (_i = 0, _len = _ref.length; _i < _len; _i++) {
      node = _ref[_i];
      _results.push(node.textContent = message);
    }
    return _results;
  }
}