When comparing Functools vs Underscore.js, the Slant community recommends Functools for most people. In the question“What are the best libraries for functional programming on Node.js?” Functools is ranked 4th while Underscore.js is ranked 16th. The most important reason people chose Functools is:
Each of the major higher-order functions also has an asynchronous counterpart included.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Asynchronous versions of functions included
Each of the major higher-order functions also has an asynchronous counterpart included.
Pro Standard higher-order functions
compose, each, filter, map, reduce, as well as a few others.
Pro Wide variety of useful utility functions
Underscore comes with not just all the usual functional suspects, but all the tools you'll need to go back-and-forth between Object Oriented and Functional paradigms - dynamically create objects from lists and vice-versa, pull data from object fields, bind 'this', partially apply, chain functions, and more.
Pro Widely used
Underscore's popularity means that it's battle-hardened and ready for production use.