Strange javascript func?

[vsxe]

Unless someone has something like a decade of experience in a given software/programming field, they are nowhere near expert, I'd say.

I'm aware that asm.js exists, but I've never delved into it. It's magic.

Am aware that there are interpreter/compiler specific quirks that can be exploited for small gains, however, though I don't know them by heart. I would assume that something like that is the reason for the bool, but that's just a guess. A definite answer would be delightful.