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.
I'm trying to modularize CSSselect and most modules depend on these functions. IMHO, having a separate module is the easiest solution to this problem.