Old (way) Octal

JavaScript has lots of numerical type support, my usual default is decimal.

Then with a lot of the byte mangling work I do, I use hex a lot, so things like 0x80 give me a little more information than just 128 because it tells me that the MSB is on when all others are off.

This works well with binary too (which frankly looks weird in JavaScript): 0b10000000.

Octal is knocking around in JavaScript, 0o40 (which is 32 - and no, I'm never quite sure when to use octal), but, TIL, octal has an "old format" in JavaScript: 040. Yep, just slap a 0 on the front and you get a different base 😱

Via Martin Kleppe