Hector Martin

What's bad faith here? This is how floating-point works. No other language does this, to my knowledge.

5.8 is about conversion to integer formats. JS doesn’t even *have* an integer format. Stringifying is not converting to an integer format, it’s converting to a string

A string which is a sequence of digits with no decimal point. That's what we humans call "an integer".

Humans maybe, ieee-754 no

String representations are for humans. The reasonable interpretation of getting a bunch of digits out of toString is "this string is a representation of an integer value". And it turns out said integer value is *not* what IEEE-754 says the integer value of the float is.

I don’t have 754 handy, but I’m pretty sure it does not consider 2**62 representable in a fp64 in the first place

Yes it does. Any integer value with less than 53 bits of significand (up until the max exponent) is representable in fp64. The definition of "representable" is simply any value you can express within a given floating point format.