I'm sorry the deprecation was a surprise. Spark.js has received very little attention in the last year, and we thought it better to move forward with a new library because renaming needed to happen anyways. I would love to hear your feedback on how we can handle this better in the future.
Because an access token can expire at any time, the only way to validate a token is to try and use it. If there was an endpoint to validate an access token, it could return "yes, valid", the token could expire immediately after, and then when you try to use the token, it does not work.
We are always open to feedback about design and implementation. Please file issues on particle-api-js if you ideas/concerns.
I can re-instate the issue tracker. It was taken down only to prevent users from filing new issues and wondering why nobody is responding. (GitHub does not let your turn off new issues without turning Issues off completely).