Hector Martin

53bit for ints, so Math.pow(2,53) is the largest int it can rep accurately

Wrong. The largest int that can be represented exactly in a 64-bit IEEE 754 floating point format is 0x1.fffffffffffffp+1023, which is an exact 309-digit integer that doesn't fit in a tweet, but can be approximated as 1.7976931348623157e+308.

64bit internal, 53bit external... this has been known for like 20yr

here, 6yr ago... http://2ality.com/2012/07/large-integers.html …

You do not understand floating point numbers. 2^53 is not the largest integer that can be represented accurately in 64-bit floats. *All* the integers *from zero to 2^53* can be represented, but *many more larger than that* can too. Just not all of them.

just read the URL i linked, it explains things very well

or... i dunno, argue with brendanhttps://twitter.com/brendaneich/status/526826278377099264?lang=en …

Yes, the URL you linked explains it: beyond 53 bits, you can only represent every 2 integers (and then every 4, then every 8, etc). But *you can still represent those integers*. The integer I'm using as an example is one such integer you *can* represent. Read it yourself again.