Luxon Manual Reference

Contributing to Luxon

General guidelines

Patches are welcome. Luxon is at this point just a baby and it could use lots of help. But before you dive in...Luxon is one of those tightly-scoped libraries where the default answer to "should this library do X?" is likely "no". So ask first! It might save you some time and energy.

Here are some vague notes on Luxon's design philosophy:

  1. We won't accept patches that can't be internationalized using the JS environment's (e.g. the browser's) native capabilities. This means that most convenient humanization features are out of scope.
  2. We try hard to have a clear definition of what Luxon does and doesn't do. With few exceptions, this is not a "do what I mean" library.
  3. Luxon shouldn't contain simple conveniences that bloat the library to save callers a couple lines of code. Write those lines in your own code.
  4. Most of the complexity of JS module loading compatibility is left to the build. If you have a "this can't be loaded in my bespoke JS module loader" problems, this isn't something you should be solving with changes to the src directory. If it's a common use case and is possible to generate with Rollup, it can get its own build command.
  5. We prefer documentation clarifications and gotchas to go in the docstrings, not in the guides on the docs page. Obviously, if the guides are wrong, they should be fixed, but we don't want them to turn into troubleshooting pages. On the other hand, making sure the method-level documentation has ample examples and notes is great.
  6. You'll need to sign a CLA as part of your first pull request to Luxon.

Building and testing

Building and testing is done through npm scripts. The tests run in Node and require Node 10+ with full-icu support. This is because some of the features available in Luxon (like internationalization and time zones) need that stuff and we test it all. On any platform, if you have Node 10 installed with full-icu, you're good to go; just run npm scripts like npm run test. But you probably don't have that, so read on.


Mac is easy: Open the terminal.

brew install node --with-full-icu
npm install

If that's for whatever reason a pain, the Linux instructions should also work, as well as the Docker ones.


There are two ways to get full-icu support in Linux: build it with that support, or provide it as a module. We'll cover the latter. Assuming you've installed Node 10:

npm install
npm install full-icu

Where scripts/test is just NODE_ICU_DATA="$(pwd)/node_modules/full-icu" npm run test, which is required for making Node load the full-icu module you just installed. You can run all the other npm scripts (e.g. npm run docs) directly; they don't require Intl support.


If you have Bash or WSL, the Linux instructions seem to work fine.

I would love to add instructions for a non-WSL install of the dev env!


In case messing with your Node environment just to run Luxon's tests is too much to ask, we've provided a Docker container. You'll need a functioning Docker environment, but the rest is easy:

./docker/npm install
./docker/npm run test

Patch basics

Once you're sure your bugfix or feature makes sense for Luxon, make sure you take these steps:

  1. Be sure to add tests and run them with scripts/test
  2. Be sure you run npm run lint! before you commit. Note this will modify your source files to line up with the style guidelines.
  3. Make sure you add or ESDoc annotations appropriately. You can run npm run docs to generate the HTML for them. They land in the build/docs directory. This also builds the markdown files in /docs into the guide on the Luxon website.
  4. To test Luxon in your browser, run npm run site and then open build/demo/global.html. You can access Luxon classes in the console like window.luxon.DateTime.
  5. To test in Node, run npm run build and then run something like var DateTime = require('./build/cjs/luxon').DateTime.

Luxon uses Husky to run the formatter on your code as a pre-commit hook. You should still run npm run lint! yourself to catch other issues, but this hook will help prevent you from failing the build with a trivial formatting error.

npm script reference

Command Function
npm run build Build all the distributable files
npm run build-node Build just for Node
npm run test Run the test suite, but see notes above
npm run format Run the Prettier formatter
npm run lint! Run the formatter and the linter
npm run docs Build the doc pages
npm run site Build the Luxon website
npm run check-doc-coverage Check whether there's full doc coverage