I don't think the site currently has an available API for developers.
In 2014 they started something bu I don't recall any newer posts about it.
https://www.chess.com/blog/webmaster/write-code-love-chess-check-out-our-developer-program
From the comments on that, it doesn't look like it lasted very long.
I was thinking about coding a chrome extension asking your api if GM Hikaru is online and alerting me about that
Unfortunately I couldn't find any information if your api is available.