Using bitwise OR 0 to floor a number

Question

A colleague of mine stumbled upon a method to floor float numbers using a bitwise or:

var a = 13.6 | 0; //a == 13

We were talking about it

Answer 1

• The specs say that it is converted to an integer:

  Let lnum be ToInt32(lval).

• Performance: this has been tested at jsperf before.

note: dead link to spec removed