neutrino-dev/docs/api

Neutrino API

When using Neutrino via the CLI, it creates an instance of the Neutrino API which picks up any presets and arguments passed on the command line. If you desire, you can also create your own instance of the Neutrino API and interact with it programmatically.

Instantiation

In order to access the Neutrino API, you must require or import it and instantiate it, passing in any preset names or paths you wish to load:

Using require:

const Neutrino = require('neutrino');
const api = new Neutrino(['neutrino-preset-react']);

Using ES imports:

import Neutrino from 'neutrino';

const api = new Neutrino(['neutrino-preset-react']);

Environment

When using the CLI, environment variables are automatically set based on the command you are using. When using the API this is not the case, and you must set it prior to calling any build commands or loading any presets.

process.env.NODE_ENV = 'production';

const api = new Neutrino();
api.build();

API

Constructor

When creating a Neutrino instance, you have the option of providing an array of presets for the API to attempt to load and merge configurations for. Each preset will attempt to be loaded from the current working directory's node_modules, nested within, by name, or relative file path. If it cannot be found, an exception will be thrown.

In addition to any provided presets, Neutrino will also attempt to load configuration data from the package.json residing in the current working directory. If this package.json contains an object at config.neutrino, this data will be merged.

.config

When constructing a Neutrino instance, a property of .config is set to be a new instance of webpack-chain. This property is then available to all presets, which subsequently augment it with their specific options. Every preset added uses this single .config to store their data, meaning that preset load order has an effect on which config values take precedence. Presets loaded later will override values set by earlier presets.

start(args)

The start() method is responsible for creating a development bundle, and when possible, starting a development server or source watcher. Prior to starting this process, Neutrino will trigger and wait for prestart events to finish. After it is complete, Neutrino will trigger and wait for start events to finish.

If the Neutrino config contains options for devServer, then a webpack-dev-server will be started. If it is configured for Node.js, then a build will be created, otherwise a Webpack source watcher will be started.

Currently any args passed to start() have no effect and will be passed through to any event handlers.

The start method will return a Promise which resolves after the build is done or development watcher has stopped, and all start events have finished.

api
  .start()
  .then(() => console.log('Exiting!'));

build(args)

The build() method is responsible for creating a bundle typically used for production. Prior to starting this process, Neutrino will trigger and wait for prebuild events to finish. After it is complete, Neutrino will trigger and wait for build events to finish.

Currently any args passed to build() have no effect and will be passed through to any event handlers.

The build method will return a Promise which resolves after the build is done and all build events have finished, or will reject if there was a failure during building.

api
  .build()
  .then(() => console.log('Saved to build/'))
  .catch(err => console.error(err));

test(args)

The test() method is responsible for gathering args needed for testing and triggering relevant events as a signal to test presets that they may run. Using the test method does nothing other than triggering these events; without a preset listening for these events, nothing will happen. Prior to starting this process, Neutrino will trigger and wait for pretest events to finish. After it is complete, Neutrino will trigger and wait for test events to finish, in which test runners will do their work.

Any args passed to test() are passed on to the event handles and typically have properties for an array of files to test, as well as a property for watching and rerunning tests.

The test method will return a Promise which resolves after all test events have finished, or will reject if there was a failure during testing.

api
  .test()
  .then(() => console.log('all passed'))
  .catch(err => console.error(err));

api
  .test({
    files: [/* ... */],
    watch: true
  })
  .then(() => console.log('all passed'));

getWebpackOptions()

While tools like webpack-chain provide a convenient API for creating Webpack configurations, this is not a format that is understandable by Webpack. With getWebpackOptions(), the webpack-chain instance at .config will be converted to an options object readable directly by Webpack. This call is cached, so subsequent calls to getWebpackOptions will result in the config being rendered only once, but the cached value returned afterwards.

api.getWebpackOptions(); // -> { ... }

emitForAll(eventName, payload)

Trigger a Promise-dependent event. For example, calling emitForAll('build') will trigger an event named build, and each event handler can return a Promise denoting when it is finished. When all events have finished, this call will resolve.

This method returns a Promise which resolves when all event handlers have also resolved.

api
  .emitForAll('custom-event')
  .then(() => console.log('All custom-events have resolved!'));

By passing an additional argument for payload, you can pass custom data to all the event handlers

api.emitForAll('custom-event', { custom: 'payload' });

// ...

neutrino.on('custom-event', (args, payload) => {
  console.log(payload.custom); // "payload"
});

handleErrors(err, stats)

This method is used internally to create a consistent console output when errors occur in the build. It will log the err property and any errors from stats if applicable, and return true or false depending on if there were errors.

This method returns a Boolean.

const failed = api.handleErrors(err, stats);

if (failed) {
  console.log('The build failed!');
}

_devServer

This method is used internally to generate an instance of webpack-dev-server during start(). It returns a promise that resolves when the process receives a SIGINT event to stop.

api
  ._devServer()
  .then(() => console.log('Exiting process...'));