kelement/config-loader

A loader for webpack configuration files

config-loader

A webpack configuration loader.

This module utilizes cosmiconfig which supports declaring a webpack configuration in a number of different file formats including; .webpackrc, webpack.config.js, and a webpack property in a package.json.

config-loader supports configuration modules which export an Object, Array, Function, Promise, and Function which returns a Promise.

The module also validates found configurations against webpack's options schema to ensure that the configuration is correct before webpack attempts to use it.

Requirements

This module requires a minimum of Node v6.9.0 and Webpack v4.0.0.

Getting Started

To begin, you'll need to install config-loader:

$ npm install @webpack-contrib/config-loader --save-dev

And get straight to loading a config:

const loader = require('@webpack-contrib/config-loader');
const options = { ... };

loader(options).then((result) => {
  // ...
  // result = { config: Object, configPath: String }
});

Extending Configuration Files

This module supports extending webpack configuration files with ESLint-style extends functionality. This feature allows users to create a "base" config and in essence, "inherit" from that base config in a separate config. A bare-bones example:

// base.config.js
module.exports = {
  name: 'base',
  mode: 'development',
  plugins: [...]
}

// webpack.config.js
module.exports = {
  extends: path.join(..., 'base-config.js'),
  name: 'dev'

The resulting configuration object would resemble:

// result
{
  name: 'dev',
  mode: 'development',
  plugins: [...]
}

The webpack.config.js file will be intelligently extended with properties from base.config.js.

The extends property also supports naming installed NPM modules which export webpack configurations. Various configuration properties can also be filtered in different ways based on need.

Read More about Extending Configuration Files

Gotchas

Function-Config Parameters

When using a configuration file that exports a Function, users of webpack-cli have become accustom to the function signature:

function config (env, argv)

webpack-cli provides any CLI flags prefixed with --env as a single object in the env parameter, which is an unnecessary feature. Environment Variables have long served the same purpose, and are easily accessible within a Node environment.

As such, config-loader does not call Function configs with the env parameter. Rather, it makes calls with only the argv parameter.

Extending Configuration Files in Symlinked Modules

When using extends to extend a configuration which exists in a different package, care must be taken to ensure you don't hit module resolution issues if you are developing with these packages with symlinks (i.e. with npm link or yarn link).

By default, Node.js does not search for modules through symlinks, and so you may experience errors such as:

module not found: Error: Can't resolve 'webpack-hot-client/client'

This can be fixed by using Node's --preserve-symlinks flag which will allow you to develop cross-module, without experiencing inconsistencies when comparing against a normal, non-linked install:

For webpack-command:

node --preserve-symlinks ./node_modules/.bin/wp

For webpack-serve:

node --preserve-symlinks ./node_modules/.bin/webpack-serve

Supported Compilers

This module can support non-standard JavaScript file formats when a compatible compiler is registered via the require option. If the option is defined, config-loader will attempt to require the specified module(s) before the target config is found and loaded.

As such, config-loader will also search for the following file extensions; .js, .es6, .flow, .mjs, and .ts.

The module is also tested with the following compilers:

• babel-register
• flow-remove-types/register
• ts-node/register

Note: Compilers are not part of or built-into this module. To use a specific compiler, you must install it and specify its use by using the --require CLI flag.

API

loader([options])

Returns a Promise, which resolves with an Object containing:

config

Type: Object

Contains the actual configuration object.

configPath

Type: String

Contains the full, absolute filesystem path to the configuration file.

Options

allowMissing

Type: Boolean
Default: false

Instructs the module to allow a missing config file, and returns an Object with empty config and configPath properties in the event a config file was not found.

configPath

Type: String Default: undefined

Specifies an absolute path to a valid configuration file on the filesystem.

cwd

Type: String Default: process.cwd()

Specifies an filesystem path from which point config-loader will begin looking for a configuration file.

require

Type: String | Array[String] Default: undefined

Specifies compiler(s) to use when loading modules from files containing the configuration. For example:

const loader = require('@webpack-contrib/config-loader');
const options = { require: 'ts-node/register' };

loader(options).then((result) => { ... });

See Supported Compilers for more information.

schema

Type: Object Default: undefined

An object containing a valid JSON Schema Definition.

By default, config-loader validates your webpack config against the webpack config schema. However, it can be useful to append additional schema data to allow configs, which contain properties not present in the webpack schema, to pass validation.

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT