Not sure if you’ve done more towards this, but jStorage caches the follower count in the browser and not the server (and therefore one person might not be able to refresh more than once a minute but 300 unique people/browsers call the site in the hour and you have an issue).
You’d have to use SQL (what I’m using in my edited version documented in my original comment [edit still under approval]) or open a file to store count (which is what I recommend for your version since you’re allowing users to implement your solution on the server, file storage requires no other requirements such as a SQL database and appropriate table).
Best,
Mike