Neutrino API¶
When using Neutrino via the CLI, it creates an instance of the Neutrino API which picks up
any middleware and arguments passed on the command line or located in your .neutrinorc.js
. If you desire, you can
also create your own instance of the Neutrino API and interact with it programmatically.
Importing¶
The default export of the Neutrino module is an object with the core Neutrino API, along with available built-in functions for the API to run:
const { Neutrino, build, inspect, start, test } = require('neutrino');
The Neutrino
function is the lowest-level API, and each of the other methods can be used with the Neutrino
API for executing their functionality. First, we will cover the Neutrino
API and
later showing how to use the runnable functions.
Instantiation¶
In order to access the Neutrino API, you must require or import it and invoke it, passing in any options:
Using require
:
const { Neutrino } = require('neutrino'); const api = Neutrino(options);
Using ES imports:
import { Neutrino } from 'neutrino'; const api = Neutrino(options);
API options¶
The Neutrino function can accept an object for setting a number of useful options.
Path options¶
The path options mentioned afterwards are generated using JavaScript object getters and setters, meaning their
assignment and access will produce a computed value each time. For example, the value set for options.source
may not
be the same as the value retrieved, as they will be path-normalized to absolute paths:
api.options.source = 'lib'; console.log(api.options.source); // /project/lib
api.options.mains.index = 'app.js'; console.log(api.options.mains.index); // /project/src/app.js api.options.source = 'lib'; console.log(api.options.mains.index); // /project/lib/app.js
options.root
¶
Set the base directory which Neutrino middleware and presets operate on. Typically this is the project directory where
the package.json would be located. If the option is not set, Neutrino defaults it to process.cwd()
. If a relative
path is specified, it will be resolved relative to process.cwd()
; absolute paths will be used as-is.
Neutrino({ // if not specified, defaults to process.cwd() // relative, resolves to process.cwd() + website root: 'website', // absolute root: '/code/website' })
options.source
¶
Set the directory which contains the application source code. If the option is not set, Neutrino defaults it to src
.
If a relative path is specified, it will be resolved relative to options.root
; absolute paths will be used as-is.
Neutrino({ // if not specified, defaults to options.root + src // relative, resolves to options.root + lib source: 'lib', // absolute source: '/code/website/lib' })
options.output
¶
Set the directory which will be the output of built assets. If the option is not set, Neutrino defaults it to build
.
If a relative path is specified, it will be resolved relative to options.root
; absolute paths will be used as-is.
Neutrino({ // if not specified, defaults to options.root + build // relative, resolves to options.root + dist output: 'dist', // absolute output: '/code/website/dist' })
options.tests
¶
Set the directory that contains test files. If the option is not set, Neutrino defaults it to test
.
If a relative path is specified, it will be resolved relative to options.root
; absolute paths will be used as-is.
Neutrino({ // if not specified, defaults to options.root + test // relative, resolves to options.root + testing tests: 'testing', // absolute tests: '/code/website/testing' })
options.mains
¶
Set the main entry points for the application. If the option is not set, Neutrino defaults it to:
{ index: 'index' }
Notice the entry point has no extension; the extension is resolved by webpack. If relative paths are specified,
they will be computed and resolved relative to options.source
; absolute paths will be used as-is.
Neutrino({ mains: { // If not specified, defaults to options.source + index.* index: 'index', // Override to relative, resolves to options.source + entry.* index: 'entry', // Override to absolute path index: '/code/website/src/entry.js' } })
Other options¶
options.debug
¶
Informs interested middleware that they should be in a state of debugging. This does not currently make Neutrino itself behave any differently, rather it can be used to inform middleware to behave differently, by outputting console information, inspecting processes, or changing configuration which is helpful for debugging.
options.env
¶
When using the CLI and the higher-level API functions, environment variables are automatically set based on the command
you are using. When using the Neutrino
low-level API this is not the case, and you should specify an env
option
to the API prior to calling any build commands or loading any middleware if you expect them to build correctly based on
their environment target.
Use options.env
to set environment variables and make them available to middleware for conditional operations.
Neutrino({ env: { NODE_ENV: 'production' } }); process.env.NODE_ENV // "production"
options.command
¶
The currently running CLI command, e.g. build
, start
, lint
, etc. This value is typically
set by the CLI when instantiating the API, but can also be set manually. This value is used by some
middleware to determine when to augment the configuration with certain functionality.
options.extensions
¶
Informs interested middleware the preferred list of module extensions to support.
By default, options.extensions
is set to ['js', 'jsx', 'vue', 'ts', 'tsx', 'mjs']
.
options.packageJson
¶
Returns the package.json
object defined at the root level of the project.
Neutrino API¶
When creating a Neutrino instance, you have the option of providing an object which can be passed as options to
middleware as neutrino.options
.
const { Neutrino } = require('neutrino'); const neutrino = Neutrino(); // or with optional options const neutrino = Neutrino({ output: 'dist' });
options
¶
An object containing various properties for the benefit of the API and middleware. This can contain options set by both Neutrino and any included middleware.
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 middleware
which subsequently augment it with their specific configuration. All middleware and presets added use this single
config
to store their data, meaning that middleware load order has an effect on which config values take precedence.
Middleware loaded first will have any configuration overridden by later middleware with matching properties.
use(middlewareFormat)
¶
Use a Neutrino middleware format, optionally providing options which will be passed to the middleware. Middleware functions will be invoked with two arguments:
- The Neutrino API instance
- Any middleware options argument passed to
use
.
Manually loading middleware with use
¶
Using the Neutrino API you can load middleware and presets (which are also just middleware)
using the use
method. The use
method takes in a middleware format and optionally any options that should be
passed to the middleware. See middleware formats for details on the different ways to
specify middleware.
/** * use:: * (Function, Object) * (String, Object) * (Array [Middleware, Object]) * (Object) */ // use :: (Function, Object) neutrino.use(neutrino => { /* ... */ }, { /* options */ }) // use :: (String, Object) neutrino.use('middleware', { /* options */ }) // use :: (Array [Middleware, Object]) neutrino.use(['middleware', { /* options */ }]) // use :: (Object) neutrino.use({ options: { /* ... */ }, use: [ // ...even more middleware ] })
Any options
passed to a middleware object format will be set on the Neutrino API instance prior to consuming any
middleware in the use
array.
Events¶
on(eventName, handler)
¶
Add a handler
function to a Neutrino instance that listens to events named eventName
. If the event handler
is going to be used with emitForAll
, ensure the handler
returns a Promise. Use the *
event name to
execute the handler for all events. Note that *
events are triggered after named events.
api.on('custom-event', () => { // ... });
off(eventName, handler)
¶
Remove a handler
function from listening to a particular eventName
, including *
events.
const handler = () => /* ... */; api.on('custom-event', handler); api.off('custom-event', handler);
emit(eventName, payload)
¶
Invoke all handlers for the given eventName
. Note that *
handlers are executed after named events. You may
also pass an optional payload
value to be passed as an argument to the associated event handler function.
api.emit('custom-event', { /* payload */ });
emitForAll(eventName, payload)
¶
Invoke all handlers for the given eventName
, meant for usage with Promise-dependent events. 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' }); // ... api.on('custom-event', (args, payload) => { console.log(payload.custom); // "payload" });
config.toConfig()
¶
While tools like webpack-chain provide a convenient API for creating webpack configurations, this is not a format that
is understandable by webpack. With config.toConfig()
, the webpack-chain instance at config
will be converted to
a configuration object readable directly by webpack.
api.config.toConfig(); // -> { ... }
register(command, handler, description = '')
¶
This method registers a new command which can be run from the API at a later time. This function takes three
arguments: a String command name, a Function which accepts a webpack configuration and the API, and an optional string
description. The return value of handler
depends on the expected usage of the command. The description is optional,
but useful when using --help
from the command line to view available commands.
The handler function can accept two arguments:
- A webpack configuration object. This is the result of calling
api.config.toConfig()
, and represents a webpack-usable object - The Neutrino API instance
_Example: add a new runnable command which resolves with a JSON-formatted webpack configuration:`
api.register( 'jsonify', config => JSON.stringify(config, null, 2), 'Output a JSON representation of the accumulated webpack configuration' );
The registered command can be triggered from call()
, run()
, or via the CLI.
require(moduleId)
¶
This method is typically used internally by the Neutrino API to attempt to require a string module ID in various paths
before failing. Takes a String moduleId
and returns the first exports of the module it is able to require. This
will throw an exception if Neutrino is unable to require the specified module ID in any of its know paths.
call(commandName)
¶
This API method will invoke a command function that has been previously defined by the register
method.
The commandName
argument should be a String. Any necessary middleware should be used prior to invoking call
.
The call
method will invoke the registered command with two arguments: a webpack configuration object, and the
instance of the Neutrino API. The return value of using call
will be the return value of invoking the registered
handler with these two arguments.
For a concrete example, the eslint middleware registers an eslintrc
command. The results of this command can be returned with call
, which is loaded within
.neutrinorc.js
in this example:
const { Neutrino } = require('neutrino'); const eslintConfig = Neutrino({ root: __dirname }) .use('.neutrinorc.js') .call('eslintrc');
run(commandName)
¶
This API method will invoke a command function that has been previously defined by the register
method.
The commandName
argument should be a String. Any necessary middleware should be used prior to invoking run
.
Every runnable command performs the following flow:
- Triggers all
pre*
event handlers for the given command name - Triggers all
prerun
event handlers - Invokes the given registered command function
- Triggers all event handlers for the given command name
- Triggers all
run
event handlers
The run
method will invoke the registered command with two arguments: a webpack configuration object, and the
instance of the Neutrino API. Calling a runnable command will return a
Future
which can then be used to kick off the above flow. This Future will
be resolved with the resolution value of the command, or rejected with any errors the command provides. The return
value from the registered command can be any synchronous value, Promise, or Future, and Neutrino will properly chain
from this.
The Neutrino package exports functions to automate key parts of interacting with the Neutrino API, and they are named
build
, inspect
, start
, and test
. These are command functions that are invoked when using the CLI.
As an example, the CLI does this similar to the following:
const { Neutrino, build } = require('neutrino'); const api = Neutrino(); api.register('build', build); // later api .use(middleware) .run('build') .fork( (errs) => { /* handle errors */ }, () => { /* handle success */ } );
_Example: execute the jsonify
command we registered in the register()
example, and resolve with a Future`:
const api = Neutrino(); const Future = require('fluture'); api.register('jsonify', config => Future.of(JSON.stringify(config, null, 2))); // ... api .run('jsonify') .fork(console.error, json => console.log(json));
_Example: execute the jsonify
command we registered in the register()
example, and resolve with a Promise`:
const api = Neutrino(); api.register('jsonify', config => Promise.resolve(JSON.stringify(config, null, 2))); // ... api .run('jsonify') .fork(console.error, json => console.log(json));
The run
method takes a single argument, a String command name which the API can execute,
which has been previously registered with register
.
Prior to starting this process, Neutrino will trigger and wait for pre{command}
and prerun
events to
finish. After it is complete, Neutrino will trigger and wait for {command}
and run
events to finish.
const { Neutrino, build } = require('neutrino'); const api = Neutrino(); api .register('build', build) .use('@neutrinojs/react') .run('build') .fork( errors => errors.forEach(console.error), stats => console.log(stats.toString({ colors: true })) );
Runnable Functions¶
The following functions are exported from Neutrino and can be registered with the API to be executed from run
(recommended) or call
. These functions are used internally by the CLI, which creates its own instance of the API and
registers them prior to run
. Since each of them can be registered directly with the API, they each have the same
signature, accepting a webpack configuration and an API instance.
start(webpackConfig, neutrinoApi)
¶
The start
function is responsible for creating a development bundle, and when possible, starting a development
server or source watcher. If the Neutrino config contains options for devServer
, then a webpack-dev-server will be
started, otherwise a webpack source watcher will be started.
The start
function returns a Future
which can then be used to
kick off the runnable flow. This Future will be resolved with a webpack compiler (for example, if you wish to listen for
additional build events), or reject with an array of errors. This resolution will be completed when the dev server
or webpack watcher has been started.
Example: using the run
method:
const { Neutrino, start } = require('neutrino'); const api = Neutrino(); api .register('start', start) .use('@neutrinojs/react') .run('start') .fork( errors => errors.forEach(err => console.error(err)), compiler => console.log('App running!') );
Example: calling start
manually:
const { Neutrino, start } = require('neutrino'); const api = Neutrino(); api.use('@neutrinojs/react'); start(api.config.toConfig(), api) .fork( errors => errors.forEach(err => console.error(err)), compiler => console.log('App running!') );
build(webpackConfig, neutrinoApi)
¶
The build
function is responsible for creating a bundle typically used for production.
The build
function returns a Future
which can then be used to
kick off the runnable flow. This Future will be resolved with a webpack stats object about the build, or reject with an
array of errors. This resolution will be completed when the build has been completed.
Example: using the run
method:
const { Neutrino, build } = require('neutrino'); const api = Neutrino(); api .register('build', build) .use('@neutrinojs/node') .run('build') .fork( errors => errors.forEach(err => console.error(err)), stats => console.log(stats.toString({ colors: true })) );
Example: calling build
manually:
const { Neutrino, build } = require('neutrino'); const api = Neutrino(); api.use('@neutrinojs/node'); build(api.config.toConfig(), api) .fork( errors => errors.forEach(err => console.error(err)), stats => console.log(stats.toString({ colors: true })) );
test(webpackConfig, neutrinoApi)
¶
The test
function is typically used for gathering middleware and options needed for testing and triggering relevant
events as a signal to test middleware that they may run. Using the test
method has no other functionality other than
performing the automated runnable flow outlined above. Since test()
does nothing other than triggering this flow,
without middleware listening for test
events, nothing will happen. For this reason, it is recommended that test
be
used with the run
method to ensure that all test-related events are properly retriggered. After Neutrino triggers and
waits for test
events to finish, the test runners will do their work and test()
can resolve.
Any args
passed to the API as options are passed on to the event handlers and typically have properties for an array
of files
to test, as well as a property for watch
ing and rerunning tests.
The test
function returns a Future
which can then be used to
kick off the runnable flow. This Future will be resolved, or reject with an error. This resolution will be completed
when the testing has been finished.
Example: Using the run
method:
const { Neutrino, test } = require('neutrino'); const api = Neutrino(); api .register('test', test) .use('@neutrinojs/node') .use('@neutrinojs/mocha') .run('test') .fork( err => console.error(err), () => console.log('Testing completed!') ); // With API args const api = Neutrino({ args: { files: [/* ... */], watch: true } }); api .register('test', test) .use('@neutrinojs/node') .use('@neutrinojs/mocha') .run('test') .fork( errors => errors.forEach(err => console.error(err)), () => console.log('Testing completed!') );
Example: calling test
manually:
const { Neutrino, test } = require('neutrino'); const api = Neutrino(); api .use('@neutrinojs/node') .use('@neutrinojs/mocha'); test(api.config.toConfig(), api) .fork( err => console.error(err), () => console.log('Testing completed!') );
inspect(webpackConfig, neutrinoApi)
¶
The inspect()
function is responsible for creating an object string which represents a webpack configuration for the
provided middleware and options. Upon execution inspect
will:
- Receive the webpack configuration object
- Deep-sort the object
- Stringify the object with 2 spaces (not JSON stringified!)
The inspect
function returns a Future
which can then be used to
kick off the runnable flow. This Future will be resolved with a string representation of the webpack config, or reject
with an error.
Example: using the run
method:
const { Neutrino, inspect } = require('neutrino'); const api = Neutrino(); api .register('inspect', inspect) .use('@neutrinojs/node') .run('inspect') .fork( errors => errors.forEach(err => console.error(err)), config => console.log(config) );
Example: calling inspect
manually:
const { Neutrino, inspect } = require('neutrino'); const api = Neutrino(); api.use('@neutrinojs/node'); inspect(api.config.toConfig(), api) .fork( err => err => console.error(err), config => console.log(config) );
Helper Methods¶
regexFromExtensions
¶
Using the Neutrino API you can get a regex expression from a list of extensions using the regexFromExtensions
method.
The regexFromExtensions
takes in an array of extensions as a parameter but can be invoked
without any parameters which fallback to neutrino.options.extensions
.
// resolves to /\.(vue|js)$/ neutrino.regexFromExtensions(['vue', 'js']); // defaults neutrino.options.extensions which resolves to /\.(js|jsx|vue|ts|tsx|mjs)$/ neutrino.regexFromExtensions();