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Neutrino Node.js Preset¶

@neutrinojs/node is a Neutrino preset that supports building Node.js applications.

Features¶

Zero upfront configuration necessary to start developing and building a Node.js project
Modern Babel compilation supporting ES modules, async functions, and dynamic imports
By default targets the version of Node.js used to run webpack
Supports automatically-wired sourcemaps
Tree-shaking to create smaller bundles
Hot Module Replacement with source-watching during development
Chunking of external dependencies apart from application code
Easily extensible to customize your project as needed

Requirements¶

Node.js v8.3+
Yarn v1.2.1+, or npm v5.4+
Neutrino v8

Installation¶

@neutrinojs/node can be installed via the Yarn or npm clients. Inside your project, make sure neutrino and @neutrinojs/node are development dependencies.

Yarn¶

❯ yarn add --dev neutrino @neutrinojs/node

npm¶

❯ npm install --save-dev neutrino @neutrinojs/node

If you want to have automatically wired sourcemaps added to your project, add source-map-support:

Yarn¶

❯ yarn add source-map-support

npm¶

❯ npm install --save source-map-support

Project Layout¶

@neutrinojs/node follows the standard project layout specified by Neutrino. This means that by default all project source code should live in a directory named src in the root of the project. This includes JavaScript files that would be available to your compiled project.

Quickstart¶

The fastest way to get started is by using the create-project scaffolding tool. Don’t want to use the CLI helper? No worries, we have you covered with the manual installation.

create-project¶

Run the following command to start the process. Substitute <directory-name> with the directory name you wish to create for this project.

Yarn¶

❯ yarn create @neutrinojs/project <directory-name>

Note: The create command is a shorthand that helps you do two things at once. See the Yarn create docs for more details.

npm/npx¶

npx comes pre-installed with npm. If you’re running an older version of npm, then npm install -g npm to update to the latest version.

❯ npx @neutrinojs/create-project <directory-name>

The CLI helper will prompt for the project to scaffold, and will offer to set up a test runner as well as linting to your project. Refer to the Create new project section for details on all available options.

Manual Installation¶

After installing Neutrino and the Node.js preset, add a new directory named src in the root of the project, with a single JS file named index.js in it.

❯ mkdir src && touch src/index.js

Edit your src/index.js file with the following:

import { createServer } from 'http';

const delay = ms => new Promise(resolve => setTimeout(resolve, ms));
const port = process.env.PORT || 3000;

createServer(async (req, res) => {
  await delay(500);
  console.log('Request!');
  res.end('hi!');
})
.listen(port, () => console.log(`Server running on port ${port}`));

Now edit your project's package.json to add commands for starting and building the application.

{
  "scripts": {
    "start": "neutrino start --use @neutrinojs/node",
    "build": "neutrino build --use @neutrinojs/node"
  }
}

If you are using .neutrinorc.js, add this preset to your use array instead of --use flags:

module.exports = {
  use: ['@neutrinojs/node']
};

Start the app, then either open a browser to http://localhost:3000 or use curl from another terminal window:

Yarn¶

❯ yarn start
Server running on port 3000

❯ curl http://localhost:3000
hi!

npm¶

❯ npm start
Server running on port 3000

❯ curl http://localhost:3000
hi!

Building¶

@neutrinojs/node builds assets to the build directory by default when running neutrino build. Using the quick start example above as a reference:

❯ yarn build

Hash: 89e4fb250fc535920ba4
Version: webpack 3.5.6
Time: 424ms
       Asset     Size  Chunks             Chunk Names
    index.js  4.29 kB       0  [emitted]  index
index.js.map  3.73 kB       0  [emitted]  index
✨  Done in 1.51s.

You can either serve or deploy the contents of this build directory as a Node.js module, server, or tool. For Node.js this usually means adding a main property to package.json pointing to the primary main built entry point. Also when publishing your project to npm, consider excluding your src directory by using the files property to whitelist build, or via .npmignore to blacklist src.

{
  "main": "build/index.js",
  "files": [
    "build"
  ]
}

Note: While this preset works well for many types of Node.js applications, it's important to make the distinction between applications and libraries. This preset will not work optimally out of the box for creating distributable libraries, and will take a little extra customization to make them suitable for that purpose.

Hot Module Replacement¶

While @neutrinojs/node supports Hot Module Replacement for your app, it does require some application-specific changes in order to operate. Your application should define split points for which to accept modules to reload using module.hot:

For example:

import { createServer } from 'http';
import app from './app';

if (module.hot) {
  module.hot.accept('./app');
}

createServer((req, res) => {
  res.end(app('example'));  
}).listen(/* */);

Or for all paths:

import { createServer } from 'http';
import app from './app';

if (module.hot) {
  module.hot.accept();
}

createServer((req, res) => {
  res.end(app('example'));  
}).listen(/* */);

Using dynamic imports with import() will automatically create split points and hot replace those modules upon modification during development.

Debugging¶

You can start the Node.js server in inspect mode to debug the process by setting neutrino.options.debug to true. This can be done from the API or the CLI using --debug.

Preset options¶

You can provide custom options and have them merged with this preset's default options to easily affect how this preset builds. You can modify Node.js preset settings from .neutrinorc.js by overriding with an options object. Use an array pair instead of a string to supply these options in .neutrinorc.js.

The following shows how you can pass an options object to the Node.js preset and override its options, showing the defaults:

module.exports = {
  use: [
    ['@neutrinojs/node', {
      // Enables Hot Module Replacement. Set to false to disable
      hot: true,

      // Target specific versions via @babel/preset-env
      targets: {
        node: '8.3'
      },

      // Remove the contents of the output directory prior to building.
      // Set to false to disable cleaning this directory
      clean: {
        paths: [neutrino.options.output]
      },

      // Add additional Babel plugins, presets, or env options
      babel: {
        // Override options for @babel/preset-env, showing defaults:
        presets: [
          ['@babel/preset-env', {
            // Targets the version of Node.js used to run webpack.
            targets: { node: 'current' },
            modules: false,
            useBuiltIns: true,
          }]
        ]
      }
    }]
  ]
};

Example: Override the Node.js Babel compilation target to Node.js v6:

module.exports = {
  use: [
    ['@neutrinojs/node', {
      // Target specific versions via @babel/preset-env
      targets: {
        node: '6.0'
      }
    }]
  ]
};

Customizing¶

To override the build configuration, start with the documentation on customization. @neutrinojs/node creates some conventions to make overriding the configuration easier once you are ready to make changes.

By default Neutrino, and therefore this preset, creates a single main index entry point to your application, and this maps to the index.* file in the src directory. This means that this preset is optimized toward a single main entry to your application. Code not imported in the hierarchy of the index entry will not be output to the bundle. To overcome this you must either define more mains via options.mains, import the code path somewhere along the index hierarchy, or define multiple configurations in your .neutrinorc.js.

Vendoring¶

This preset automatically vendors all external dependencies into a separate chunk based on their inclusion in your package.json. No extra work is required to make this work.

Rules¶

The following is a list of rules and their identifiers which can be overridden:

Name	Description	Environments and Commands
`compile`	Compiles JS files from the `src` directory using Babel. Contains a single loader named `babel`	all

Plugins¶

The following is a list of plugins and their identifiers which can be overridden:

Note: Some plugins are only available in certain environments. To override them, they should be modified conditionally.

Name	Description	Environments and Commands
`banner`	Injects source-map-support into the mains (entry points) of your application if detected in `dependencies` or `devDependencies` of your package.json.	Only when `source-map-support` is installed
`clean`	Clears the contents of `build` prior to creating a production bundle.	`build` command
`start-server`	Start a Node.js for the first configured main entry point.	`start` command
`hot`	Enables Hot Module Replacement.	`start` command

Override configuration¶

By following the customization guide and knowing the rule, loader, and plugin IDs above, you can override and augment the build by by providing a function to your .neutrinorc.js use array. You can also make these changes from the Neutrino API in custom middleware.

Example: Allow importing modules with a .esm extension.

module.exports = {
  use: [
    '@neutrinojs/node',
    (neutrino) => neutrino.config.resolve.extensions.add('.esm')
  ]
};

Contributing¶

This preset is part of the neutrino-dev repository, a monorepo containing all resources for developing Neutrino and its core presets and middleware. Follow the contributing guide for details.