Express.js with Babel Boilerplate
A mostly unopinionated starter project for using Babel and ES2017+ features in a Node.js server environment as well as providing linting and testing solutions. It provides the setup for compiling, linting and testing your code but doesn't make any further assumptions on how your project should be structured.
Make sure you read the FAQ for more details and info.
- Express.js as the web framework.
- ES2017+ support with Babel.
- Automatic polyfill requires based on environment with babel-preset-env.
- Linting with ESLint.
- Testing with Jest.
- Quick deployment guide for Heroku, AWS Elastic Beanstalk, and App Engine.
# Clone the project git clone firstname.lastname@example.org:vmasto/express-babel.git cd express-babel # Make it your own rm -rf .git && git init && npm init # Install dependencies npm install # or if you're using Yarn yarn
Then you can begin development:
# yarn yarn run dev # npm npm run dev
This will launch a nodemon process for automatic server restarts when your code changes.
Start the test runner in watch mode with:
# yarn yarn test # npm npm test
You can also generate coverage with:
# yarn yarn test --coverage # npm npm test -- --coverage
Begin linting in watch mode with:
# yarn yarn run lint # npm npm run lint
To begin linting and start the server simultaneously, edit the
package.json like this:
"dev": "nodemon src/index.js --exec \"node -r dotenv/config -r babel-register\" | npm run lint"
Environmental variables in development
The project uses dotenv for setting environmental variables during development. Simply copy
.env.example, rename it to
.env and add your env vars as you see fit.
It is strongly recommended never to check in your .env file to version control. It should only include environment-specific values such as database passwords or API keys used in development. Your production env variables should be different and be set differently depending on your hosting solution.
dotenv is only for development.
Deployment is specific to hosting platform/provider but generally:
# yarn yarn run build # npm npm run build
will compile your
# yarn yarn start # npm npm start
build (via the
prestart hook) and start the compiled application from the
The last command is generally what most hosting providers use to start your application when deployed, so it should take care of everything.
You can find small guides for Heroku, App Engine and AWS in the deployment document.
Tips / Debugging
Where is all the configuration for ESLint, Jest and Babel?
package.json. Feel free to extract them in separate respective config files if you like.
Why are you using
babel-register instead of
babel-node contains a small "trap", it loads Babel's polyfill by default. This means that if you use something that needs to be polyfilled, it'll work just fine in development (because
babel-node polyfills it automatically) but it'll break in production because it needs to be explicitely included in Babel's CLI which handles the final build.
In order to avoid such confusions,
babel-register is a more sensible approach in keeping the development and production runtimes equal. By using babel-preset-env only code that's not supported by the running environment is transpiled and any polyfills required are automatically inserted.
Should I use this?
Full disclosure: If you have to ask perhaps you should reconsider. There is some debate on whether to use Babel-transpiled code on the server or not. Personally, I think it's fine and I've found this setup to be a sensible approach in doing so. That said, I'd suggest to take anything you read online with a grain of salt and refrain from blindly using boilerplates without first investigating personally.
Node is very rapidly converging with the latest ECMAScript specification, and there's mostly full native support for ES2015 and ES2016. The need to transpile on the server is way smaller nowadays, albeit the language is constantly improving and transpiling will probably always be a part of our workflow. At the time of this writing the main benefits are mainly ES6 module syntax and async/await without flags.
In any case, you can simply remove transpilation and keep everything else that this kit has to offer.
If you see anything that needs improvement feel free to open an issue for discussion!
You can also find me on twitter at @vmasto.
MIT License. See the LICENSE file.