uechi.io/source/_drafts/parseint-magic.md

title
[].map(parseInt)

Fan fact

[0xa, 0xa, 0xa].map(parseInt) results in [10, NaN, 2].

Why???

parseInt(0xa, 0, [0xa, 0xa, 0xa])

The second argument is 0 so the first argument gonna be treated as decimal number becoming 10.

parseInt(0xa, 1, [0xa, 0xa, 0xa])

The second argument is 1 which is invalid as a radix so the result ends up with NaN.

parseInt(0xa, 2, [0xa, 0xa, 0xa])

The second argument is 2 meaning the first argument going to be handled as a binary number. 0xa is 10 in binary, which results in 2 in decimal form.