[jorisd]

One thing I've noticed is that in the past, performance advice was given for specific engines (e.g. V8/crankshaft). Nowadays, if any performance advice is given, it's applicable to all major JavaScript engines, and in general the advice is for developers to write "idiomatic JavaScript", leaving the optimization to the engines.

[Klathmon]

There's a question of what came first there.

I have a feeling those optimizations apply to all engines because they applied to V8, and maintainers of the other engines attempted to match their performance since so many were coding for performance on V8 only.