Tip: Use Bit to discover and install specific functions from these libraries. You can find many of them in the Bit community, or share your own. Take a look.
Lodash - Lodash, NPM’s most downloaded and most dependent-upon package, was built to provide more consistent cross-environment iteration support for arrays, strings, objects, and arguments objects.
Ramda - This JS utility library is designed for functional programming, making it easy to create functional pipelines that don’t mutate user data.
Worth Noting: Immutable.js
ChanceJS - Chance is a minimalist generator of random strings, numbers, etc. to help reduce some monotony, while writing automated tests or anywhere else you need anything random.
ChartJS - chart.js is a great example of how sometimes less is more with 8 different data visualization types, each of them animated and customizable.