Technically TCO is still in the spec, TC39 deadlocked over modifying it. TC39 really does not fill me with confidence in general.
replyES6 class syntax is still mostly just syntax sugar overtop prototypical inheritance.
replyJS _does_ still have TCO (called Proper Tail Calls), Safari's JavaScriptCore implements it, and is technically the only conforming interpreter.
Yes but the syntax encourages patterns which would be uncommon in pre-ES6 JS.
replyI can’t rely on TCO if chromium doesn’t have it.