Board Thread:Support Requests - Getting Technical/@comment-38414343-20200327042151/@comment-9605025-20200327043347

JS support is the responsibility of the user's web browser, not Fandom. If you are asking because you want to know which version of JS you can use, then there is no single answer as it could potentially vary between users. That said, I have been told that the interactive editor available on the legacy Fandom platform is designed to recognize ES3 and earlier. The ability to add custom JS to a wiki is not yet available to wikis using the UCP.