[bcherny]

For == vs === use a linter, same as you would for warts in other languages.

What's the issue with undefined - is it that you would use null instead?

I don't feel a need for integer type, but maybe that's because I grew up on JS. Integers feel like warts to me in a lot of cases, ie why would 2/3 == 1?

[ridiculous_fish]

2/3 === .666666666666666629659232512495 is probably worse, because it can seduce you into thinking it's accurate. Why is `2 / 3 * 3 === 3`, but `1 / 3 * 3 < 3`?

JS's floating-point-or-bust, combined with some weird Math semantics, makes it challenging to write numerically correct functions.

[bcherny]

That's a fair point. Which language do you think does it better, or is there a library you like to use (eg. Haskell's scientific type)?

[ridiculous_fish]

Floating point tends to break all sorts of assumptions. For languages without static types, bignum integers and distinct operators for truncating vs FP division is probably best. This is how Python 3 works, plus Haskell and SML (with static types).