~ is bitwise NOT. For a number it returns the ones complement: ~N = -(N+1) So ~~num I think would return the original value. The only reason I can see would be

~ is bitwise NOT. For a number it returns the ones complement: ~N = -(N+1) So ~~num I think would return the original value. The only reason I can see would be to coerce it into some kind of number type.