Functional-Light JavaScript by getify
Pragmatic, balanced FP in JavaScript. @FLJSBook on twitter.
About Functional-Light JavaScript
From the project's README at github.com/getify/Functional-Light-JS. Lightly cleaned for readability; for the full source see the upstream repo.
This book is a balanced, pragmatic look at FP in JavaScript. The first edition is now complete. Read here online for free, or:
"Functional-Light JavaScript" explores the core principles of functional programming (FP) as they are applied to JavaScript. But what makes this book different is that we approach these principles without drowning in all the heavy terminology. We look at a subset of FP foundational concepts that I call "Functional-Light Programming" (FLP) and apply it to JavaScript.
Note: Despite the word "Light" in the title, I do not consider or recommend this book as a "beginner", "easy", or "intro" book on the topic. This
Health score breakdown
6-dimension composite. See methodology for formula and weights.
Adoption signals
Real-world usage data, pulled from each registry. The bigger the numbers, the more battle-tested the project.
| Signal | Value | Source |
|---|---|---|
| GitHub stars | 17k | github.com/getify/Functional-Light-JS |
| GitHub forks | 1.9k | github.com/getify/Functional-Light-JS |
| NPM downloads (last month) | 17 | functional-light-js |
Release & maintenance
Is this project actively maintained, or about to die? Check the recency of last commit and last release.
| Project age | 9.9 years | since Aug 2016 |
| Last commit | 2.5 years ago | Dec 26, 2023 |
| Funding links | 4 | declared by maintainers |
Self-hosting cost across providers
Detected requirements: 4GB RAM, 40GB disk minimum. Cheapest plan per provider that meets the requirement.
| Provider | Plan | Specs | Monthly | |
|---|---|---|---|---|
| hetzner | CAX11 | 2c · 4GB · 40GB | $4.13 USD | Deploy → |
| vultr | VC2 | 1c · 1GB · 25GB | $5 USD | Deploy → |
| linode | Nanode 1GB | 1c · 1GB · 25GB | $5.12 USD | Deploy → |
| digitalocean | Basic Regular 1GB | 1c · 1GB · 25GB | $6 USD | Deploy → |
Ready to self-host Functional-Light JavaScript?
Spin up a hetzner CAX11 (4GB RAM, 40GB disk) for $4.13/mo and follow the project's official install docs.
Data last refreshed Jun 21, 2026.
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