Question mark and colon in JavaScript

Question

I came across the following line

hsb.s = max != 0 ? 255 * delta / max : 0;

What do the ? and : mean in this conte

Answer 1

Be careful with this. A -1 evaluates to true although -1 != true and -1 != false. Trust me, I've seen it happen.

so

-1 ? "true side" : "false side"

evaluates to "true side"