The following libraries allow us to take advantage of immutability in TypeScript:
| Library | Description | Link |
| Ramda | A practical pure functional library for JavaScript programmers. | https://github.com/ramda/ramda |
| fp-ts | Pure functional programming utilities for TypeScript applications. | https://github.com/gcanti/fp-ts |
| Underscore | A collection of helper functions that includes some functional programming helpers. | https://github.com/jashkenas/underscore |
| Lodash | A collection of helper functions that includes some functional programming helpers. | https://github.com/lodash/lodash |
| wu.js | Higher-order functions for ES6 iterators. | https://github.com/fitzgen/wu.js/ |