node_modules/boolbase/README.md

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

###WTF?

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.

###And why is this a separate module?

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.