How did you come up with the round brackets? The semicolon ist also wrong.

Objects come with curly brackets and arrays with square brackets. Your string will work with the 2 issues corrected. The values can be accessed with response.userblock, response.fileName ...
There is no "message" in the response, so you wont get anything there.

You should use the json_encode function in PHP. It might also be a good idea to also catch errors.