module-alias

What is module-alias?

The module-alias package is used to create aliases of directory paths, allowing you to simplify the require/import statements in your Node.js projects. This can be particularly useful for projects with deep directory structures, making the code cleaner and easier to maintain.

What are module-alias's main functionalities?

Registering Aliases

This feature allows you to register aliases for directories so that you can require modules using the alias instead of relative paths.

require('module-alias/register');
moduleAlias.addAliases({
  '@root'      : __dirname,
  '@models'    : __dirname + '/models',
  '@controllers': __dirname + '/controllers',
  '@lib'       : __dirname + '/lib'
});

Customizing Aliases with package.json

You can also define aliases directly in your package.json file, which module-alias will read and use to resolve modules.

{
  "_moduleAliases": {
    "@root": ".",
    "@models": "./models",
    "@controllers": "./controllers",
    "@lib": "./lib"
  }
}

Requiring Modules with Aliases

Once aliases are set up, you can require modules using the defined aliases, making the require statements much cleaner and easier to understand.

const User = require('@models/user');

Other packages similar to module-alias

require-alias

This package allows you to alias module paths in Node.js, similar to module-alias. It provides a way to keep your require calls clean. However, it is not as widely used or as well-maintained as module-alias.

babel-plugin-module-resolver

This Babel plugin allows you to add new 'root' directories that contain your modules. It also lets you map a module to another module or filepath. It is more flexible than module-alias as it integrates with Babel and supports both Node.js and frontend JavaScript projects.

link-module-alias

This package provides similar functionality to module-alias, allowing you to define aliases for your modules and directories. It differs in the way it sets up the aliases, using symbolic links, which can be more compatible with certain tools that do not understand module resolution.

README

module-alias

Allows to register aliases of directories and custom module paths in NodeJS.

This package is highly inspired by app-module-path package and it's totally backwards compatible with it. The main difference is that this package also allows creating aliases of directories for further usage with require/import

Install

npm i --save module-alias

Usage

Add these lines to your package.json (in your application's root)

"_moduleDirectories": ["node_modules_custom"],
"_moduleAliases": {
  "@root"      : "", // Application's root
  "@client"    : "src/client",
  "@admin"     : "src/client/admin",
  "@deep"      : "src/some/very/deep/directory",
  "@my_module" : "src/some-file.js",
  "something"  : "src/foo", // Or without @. Actually, it could be any string
}

And these line at the very main file of your app, before any code

import 'module-alias/register'

// And you're all set, now you can do stuff like
import 'something'
import module from '@root/some-module'
import veryDeepModule from '@bar/my-module'
import myModule from '@my_module' // module from `node_modules_custom` directory

Advanced usage

import moduleAlias from 'module-alias'

//
// Register alias
//
moduleAlias.addAlias('@client', __dirname + '/src/client')

// Or multiple aliases
moduleAlias.addAliases({
  '@root'  : __dirname,
  '@client': __dirname + '/src/client',
  ...
})

//
// Register custom modules directory (like node_modules, but
// with your own modules)
//
moduleAlias.addPath(__dirname + '/node_modules_custom')
moduleAlias.addPath(__dirname + '/src')

//
// Import settings from package.json
//
moduleAlias(__dirname + '/package.json')

// Or let mudule-alias to figure where your package.json is
// located. By default it will look in the same directory
// where you have your node_modules (application's root)
moduleAlias()

Usage with WebPack

// webpack.config.js
const npm_package = require('./package.json')

module.exports = {
  entry: { ... },
  resolve: {
    root: __dirname,
    alias: npm_package._moduleAliases || {},
    extensions: ['', '.js', '.jsx'],
    modulesDirectories: npm_package._moduleDirectories || [] // eg: ["node_modules", "node_modules_custom", "src"]
  }
}

How it works?

In order to register a custom modules path (addPath) it modifies the internal Module._nodeModulePaths method so that the directory then acts like it's the node_modules directory.

In order to register an alias it modifies the internal Module._resolveFilename method so that when you fire require or import it first checks whether the given string starts with one of the registered aliases, if so, it then replaces the alias in the string with the target path of the alias

Tags

Require alias, node import alias, node custom module directory, node local require paths, register module directory in nodejs