Neutrino Node.js Preset

neutrino-preset-node is a Neutrino preset that supports building Node.js applications.

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Features

  • Zero upfront configuration necessary to start developing and building a Node.js project
  • Modern Babel compilation supporting ES modules, Node.js 6.10+, async functions, and dynamic imports
  • 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 v6.10+
  • Yarn or npm client
  • Neutrino v7

Installation

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

Yarn

❯ yarn add --dev neutrino neutrino-preset-node

npm

npm install --save-dev neutrino neutrino-preset-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

neutrino-preset-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

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 neutrino-preset-node",
    "build": "neutrino build --use neutrino-preset-node"
  }
}

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

module.exports = {
  use: ['neutrino-preset-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

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

❯ yarn build

clean-webpack-plugin: /node/build has been removed.
Build completed in 0.419s

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 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 neutrino-preset-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: [
    ['neutrino-preset-node', {
      // Enables Hot Module Replacement. Set to false to disable
      hot: true,

      polyfills: {
        // Enables fast-async polyfill. Set to false to disable
        async: true
      },

      // Add additional Babel plugins, presets, or env options
      babel: {
        // Override options for babel-preset-env, showing defaults:
        presetEnv: {
          targets: {
            node: '6.10',
            modules: false,
            useBuiltIns: true,
            // These are excluded when using polyfills.async. Disabling the async polyfill
            // will remove these from the exclusion list
            exclude: ['transform-regenerator', 'transform-async-to-generator']
          }
        }
      }
    }]
  ]
};

Example: Override the Node.js Babel compilation target to Node.js v8:

module.exports = {
  use: [
    ['neutrino-preset-node', {
      // Add additional Babel plugins, presets, or env options
      babel: {
        // Override options for babel-preset-env
        presets: [
          ['babel-preset-env', {
            // Passing in targets to babel-preset-env will replace them
            // instead of merging them
            targets: {
              node: '8.0'
            }
          }]
        ]
      }
    }]
  ]
};

Customizing

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

By default the Node.js 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 the Node.js preset is optimized toward a main entry to your app. 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 entry points, or import the code path somewhere along the index hierarchy.

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 entry point of your application if detected in dependencies or devDependencies of your package.json. Only when source-map-support is installed
copy Copies all files from src/static to build when using neutrino build. build command
clean Clears the contents of build prior to creating a production bundle. build command
start-server Start a Node.js for a configured entry point or specified file. start command
hot Enables Hot Module Replacement. start command
named-modules Enables named modules for improved debugging and console output. From neutrino-middleware-hot. start command
module-concat Concatenate the scope of all your modules into one closure and allow for your code to have a faster execution time in the browser. NODE_ENV production

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 .mjs extension.

module.exports = {
  use: [
    'neutrino-preset-node',
    (neutrino) => neutrino.config.resolve.extensions.add('.mjs')
  ]
};

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.

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