[jasonthevillain]

I've learned the hard way to check Babel's output for sanity.

Sometimes its fine.

Other times it's madness or pulls in a massive polyfill. That's sort of inherent to making a transpiler: they need to match the spec. I usually just need one specific behavior that could be written in a 3 line helper function.

[Klathmon]

They have a "loose" mode for most compilations that can benefit from them.

In loose mode they might not follow the letter of the spec, but can cheat for speed or size.

[hzoo]

Yep you got that right!

Only thing I can think of (since changing the default to be non-spec would be odd) is just warning on larger code size outputs and saying you could try loose mode in certain plugins/situations. Lastly would be do start creating a tool that does runtime checks to determine how small the compiled output should be