This very simple module provides two basic functions, one that always returns true (trueFunc) and one that always returns false (falseFunc).

By having only a single instance of these functions around, it's possible to do some nice optimizations. Eg. CSSselect uses these functions to determine whether a selector won't match any elements. If that's the case, the DOM doesn't even have to be touched.

Node.js is an event-based server-side JavaScript engine.