enhanced-resolve

What is enhanced-resolve?

The enhanced-resolve package is a highly configurable module resolution library for Node.js, which is used by webpack under the hood. It resolves a path to a file or directory in a file system. It can handle complex resolution patterns like module aliases, extensions, and directories with package.json files.

What are enhanced-resolve's main functionalities?

File Resolution

Resolves the path to a file, taking into account file extensions and processing according to the configuration provided.

const { ResolverFactory } = require('enhanced-resolve');

const resolver = ResolverFactory.createResolver({
  fileSystem: require('fs'),
  extensions: ['.js', '.json']
});

resolver.resolve({}, __dirname, './path/to/file', (err, result) => {
  if (err) console.error(err);
  else console.log(result);
});

Directory Resolution

Resolves the path to a directory, looking for the 'main' field in the package.json or index.js within that directory.

const { ResolverFactory } = require('enhanced-resolve');

const resolver = ResolverFactory.createResolver({
  fileSystem: require('fs'),
  mainFields: ['main']
});

resolver.resolve({}, __dirname, './path/to/directory', (err, result) => {
  if (err) console.error(err);
  else console.log(result);
});

Plugin System

Allows the use of plugins to extend or modify the resolution behavior, providing a high degree of customization.

const { ResolverFactory } = require('enhanced-resolve');
const MyPlugin = require('./MyPlugin');

const resolver = ResolverFactory.createResolver({
  fileSystem: require('fs'),
  plugins: [new MyPlugin()] // Custom plugin to modify resolution behavior
});

// Use the resolver as before

Other packages similar to enhanced-resolve

resolve

A simple module resolution package that can be used to resolve file paths similarly to Node's 'require.resolve'. It is less configurable than enhanced-resolve but is easier to use for simple resolution tasks.

browser-resolve

A browser-focused module resolver that aims to replicate Node's 'require.resolve' behavior for browser environments. It is similar to enhanced-resolve but with a focus on resolving modules for bundling in the browser.

require-resolve

This package provides a function to resolve a module path relative to a given path. It is a simpler alternative to enhanced-resolve, focusing on resolving require paths without the extensive configuration options.

README

enhanced-resolve

Offers a async require.resolve function. It's highly configurable.

Features

• plugin system
• provide a custom filesystem
• sync and async node.js filesystems included

Tests

npm test

Contributing

Take a look at lib/ResolveFactory.js to understand how everything fits together. It provides a createResolver(options) function and these are the possible options:

Field	Default	Description
modules	["node_modules"]	A list of directories to resolve modules from, can be absolute path or folder name
descriptionFiles	["package.json"]	A list of description files to read from
plugins	[]	A list of additional resolve plugins which should be applied
mainFields	["main"]	A list of main fields in description files
aliasFields	[]	A list of alias fields in description files
mainFiles	["index"]	A list of main files in directories
extensions	[".js", ".json", ".node"]	A list of extensions which should be tried for files
enforceExtension	false	Enforce that a extension from extensions must be used
moduleExtensions	[]	A list of module extensions which should be tried for modules
enforceModuleExtension	false	Enforce that a extension from moduleExtensions must be used
alias	[]	A list of module alias configurations or an object which maps key to value
resolveToContext	false	Resolve to a context instead of a file
unsafeCache	false	Use this cache object to unsafely cache the successful requests
cacheWithContext	true	If unsafe cache is enabled, includes request.context in the cache key
cachePredicate	function() { return true };	A function which decides whether a request should be cached or not. An object is passed to the function with path and request properties.
fileSystem		The file system which should be used
resolver	undefined	A prepared Resolver to which the plugins are attached

The options are passed from the resolve key of your webpack configuration e.g.:

resolve: {
  extensions: ['', '.js', '.jsx'],
  modules: ['src', 'node_modules'],
  plugins: [new DirectoryNamedWebpackPlugin()]
  ...
},

License

Copyright (c) 2012-2016 Tobias Koppers

MIT (http://www.opensource.org/licenses/mit-license.php)