You'll have to put the file somewhere (e.g. a server) and request the file via ajax. The file could be for example a dictionary or array.
1. Load file via AJAX
2. Load it into array/dictionary object
3. Access the values as per the documentation
For a dictionary it would look something like this
choose(rgb(Dictionary.get("r1"),Dictionary.get("g1"),Dictionary.get("b1"), Dictionary.get("r2"),.....))