What is this asm style “x | 0” some javascript programmers are now using?

Question

I\'ve seen some performance critical javascript code, like the one on this project that makes extensive use of bitwise OR operations with 0. Ex:

GameBoyAdvan         


        

Answer 1

| operator is bitwise OR. It's used to do a bit by bit OR operation on two integers.

The usage here is a shortcut very similar to logical OR || operator to provide default value, with the exception that the result is integer only (as opposed to string...etc)

address = address | 0;

means "if address is a number, let's use it; otherwise, set it to 0".