Example Node Server w/ Babel

Getting Started

First we'll install @babel/cli, @babel/core and @babel/preset-env.

$ npm install --save-dev @babel/cli @babel/core @babel/preset-env

Then we'll create a .babelrc file for configuring babel.

$ touch .babelrc

This will host any options we might want to configure babel with.

{
  "presets": ["@babel/preset-env"]
}

Then create our server in index.js.

$ touch index.js

import http from 'http';

const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(1337, '127.0.0.1');

console.log('Server running at http://127.0.0.1:1337/');

export default server;

With recent changes to babel, you will need to transpile your ES6 before node can run it.

So, we'll add our first script, build, in package.json.

  "scripts": {
+   "build": "babel index.js -d dist"
  }

Then we'll add our start script in package.json.

  "scripts": {
   "build": "babel index.js -d dist",
+   "start": "npm run build && node dist/index.js"
  }

Now let's start our server.

$ npm start

You should now be able to visit http://127.0.0.1:1337 and see Hello World.

Watching file changes with nodemon

We can improve our npm start script with nodemon.

$ npm install --save-dev nodemon

Then we can update our npm start script.

  "scripts": {
    "build": "babel index.js -d dist",
-   "start": "npm run build && node dist/index.js"
+   "start": "npm run build && nodemon dist/index.js"
  }

Then we'll restart our server.

$ npm start

You should now be able to make changes to index.js and our server should be restarted automatically by nodemon.

Go ahead and replace Hello World with Hello {{YOUR_NAME_HERE}} while our server is running.

If you visit http://127.0.0.1:1337 you should see our server greeting you.

Getting ready for production use

First let's move our server index.js file to lib/index.js.

$ mkdir lib
$ mv index.js lib/index.js

And update our npm start script to reflect the location change.

  "scripts": {
-   "build": "babel index.js -d dist",
+   "build": "babel lib -d dist",
    "start": "npm run build && nodemon dist/index.js"
  }

Next let's add a new task: npm run serve.

  "scripts": {
    "build": "babel lib -d dist",
    "start": "npm run build && nodemon dist/index.js",
+   "serve": "node dist/index.js"
  }

Now we can use npm run build for precompiling our assets, and npm run serve for starting our server in production.

$ npm run build
$ npm run serve

This means we can quickly restart our server without waiting for babel to recompile our files.

Oh, let's not forget to add dist to our .gitignore file:

$ touch .gitignore

dist

This will make sure we don't accidentally commit our built files to git.

Testing the server

Finally let's make sure our server is well tested.

Let's install mocha.

$ npm install --save-dev mocha

And create our test in test/index.js.

$ mkdir test
$ touch test/index.js

import http from 'http';
import assert from 'assert';

import server from '../lib/index.js';

describe('Example Node Server', () => {
  it('should return 200', done => {
    http.get('http://127.0.0.1:1337', res => {
      assert.equal(200, res.statusCode);
      server.close();
      done();
    });
  });
});

Next, install @babel/register for the require hook.

$ npm install --save-dev @babel/register

Then we can add an npm test script.

  "scripts": {
    "start": "nodemon lib/index.js --exec babel-node",
    "build": "babel lib -d dist",
    "serve": "node dist/index.js",
+   "test": "mocha --require @babel/register"
  }

Now let's run our tests.

$ npm test

You should see the following:

Server running at http://127.0.0.1:1337/

  Example Node Server
    ✓ should return 200

  1 passing (43ms)

That's it!