I would use an array or a global dictionary. Probably a dictionary.
https://www.scirra.com/manual/140/dictionary
If you want it to persist, grab it's data AsJSON when it changes, and store it in a webstorage key. Then recall it when the game first starts (you can set a dictionary from JSON).
https://www.scirra.com/manual/120/webstorage
Global dictionaries can also be a good alternative to global variables in certain cases. Just FYI.