Neutrino React Preset

@neutrinojs/react is a Neutrino preset that supports building React web applications.

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  • Zero upfront configuration necessary to start developing and building a React web app
  • Modern Babel compilation adding JSX and class properties support to the features provided by @neutrinojs/web.
  • Support for React Hot Loader
  • Write JSX in .js or .jsx files
  • Automatic import of React.createElement, no need to import react or React.createElement yourself
  • Extends from @neutrinojs/web
    • Modern Babel compilation supporting ES modules, last 2 major browser versions, async functions, object rest spread syntax, and dynamic imports
    • webpack loaders for importing HTML, CSS, images, icons, fonts, and web workers
    • webpack Dev Server during development
    • Automatic creation of HTML pages, no templating necessary
    • Automatic stylesheet extraction; importing stylesheets into modules creates bundled external stylesheets
    • Pre-configured to support CSS Modules via *.module.css file extensions
    • Hot Module Replacement support including CSS
    • Tree-shaking to create smaller bundles
    • Production-optimized bundles with Babel minification, easy chunking, and scope-hoisted modules for faster execution
    • Easily extensible to customize your project as needed


  • Node.js v6 LTS, v8, v9
  • Yarn v1.2.1+, or npm v5.4+
  • Neutrino v8


@neutrinojs/react can be installed via the Yarn or npm clients. Inside your project, make sure neutrino and @neutrinojs/react are development dependencies. You will also need React and React DOM for actual React development.


❯ yarn add --dev neutrino @neutrinojs/react
❯ yarn add react react-dom


npm install --save-dev neutrino @neutrinojs/react
❯ npm install --save react react-dom

Project Layout

@neutrinojs/react 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, CSS stylesheets, images, and any other assets that would be available to import your compiled project.


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.


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


❯ 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.


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 React 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

This React preset exposes an element in the page with an ID of root to which you can mount your application. Edit your src/index.js file with the following:

import { render } from 'react-dom';

render(<h1>Hello world!</h1>, document.getElementById('root'));

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

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

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

module.exports = {
  use: ['@neutrinojs/react']

Start the app, then open a browser to the address in the console:


❯ yarn start
✔ Development server running on: http://localhost:5000
✔ Build completed


npm start
✔ Development server running on: http://localhost:5000
✔ Build completed


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

❯ yarn build

✔ Building project completed
Hash: b26ff013b5a2d5f7b824
Version: webpack 3.5.6
Time: 9773ms
                           Asset       Size    Chunks             Chunk Names
   index.dfbad882ab3d86bfd747.js     181 kB     index  [emitted]  index
 runtime.3d9f9d2453f192a2b10f.js    1.51 kB   runtime  [emitted]  runtime
                      index.html  846 bytes            [emitted]
✨  Done in 14.62s.

You can either serve or deploy the contents of this build directory as a static site.

Static assets

If you wish to copy files to the build directory that are not imported from application code, you can place them in a directory within src called static. All files in this directory will be copied from src/static to build/static. To change this behavior, specify your own patterns with @neutrinojs/copy.


The @neutrinojs/web preset loads assets relative to the path of your application by setting webpack's output.publicPath to ./. If you wish to load assets instead from a CDN, or if you wish to change to an absolute path for your application, customize your build to override output.publicPath. See the Customizing section below.

For details on merging and overriding Babel configuration, such as supporting decorator syntax, read more about using the compile-loader merge once you are comfortable customizing your build.

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 React 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 React preset and override its options. See the Web documentation for specific options you can override with this object.

module.exports = {
  use: [
    ['@neutrinojs/react', {
      /* preset options */

      // Example: disable Hot Module Replacement
      hot: false,

      // Example: change the page title
      html: {
        title: 'Epic React App'

      // Target specific browsers with babel-preset-env
      targets: {
        browsers: [
          'last 1 Chrome versions',
          'last 1 Firefox versions'

      // Add additional Babel plugins, presets, or env options
      babel: {
        // Override options for babel-preset-env:
        presets: [
          ['babel-preset-env', {
            modules: false,
            useBuiltIns: true,
            exclude: ['transform-regenerator', 'transform-async-to-generator'],


To override the build configuration, start with the documentation on customization. @neutrinojs/react does not use any additional named rules, loaders, or plugins that aren't already in use by the Web preset. See the Web documentation customization for preset-specific configuration to override.

For details on merging and overriding Babel configuration, such as supporting decorator syntax, read more about using the compile-loader merge once you are comfortable customizing your build.

Advanced configuration

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

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. The extension is resolved by webpack. This value is provided by neutrino.options.mains at neutrino.options.mains.index. This means that the Web preset is optimized toward the use case of single-page applications over multi-page applications. If you wish to output multiple pages, you can detail all your mains in your .neutrinorc.js.

module.exports = {
  options: {
    mains: {
      index: 'index', // outputs index.html from src/index.*
      admin: 'admin', // outputs admin.html from src/admin.*
      account: 'user' // outputs account.html from src/user.*
  use: ['@neutrinojs/react']


By defining an entry point named vendor you can split out external dependencies into a chunk separate from your application code.

Example: Put React and React DOM into a separate "vendor" chunk:

module.exports = {
  use: [
    (neutrino) => neutrino.config

Hot Module Replacement

While @neutrinojs/react supports Hot Module Replacement your app using React Hot Loader, it does require some application-specific changes in order to operate.

First, install react-hot-loader as a dependency, this must be React Hot Loader v3+:


❯ yarn add react-hot-loader


npm install --save react-hot-loader

From your main entry point (defaults to src/index.* from neutrino.options.mains.index), import an AppContainer from react-hot-loader. The main file may be named index.js or index.jsx. The extension is resolved by webpack.

  • Wrap your top-level React component in the AppContainer.
  • Perform the application render in a reusable function for initial load and subsequent reloads.
  • Add the hot acceptance to call this function.

For example:

import { render } from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import MyApp from './MyApp';

const load = () => render((
    <MyApp />
), document.getElementById('root'));

if ( {'./MyApp', load);



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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