babel-plugin-module-resolver

A Babel plugin to add a new resolver for your modules when compiling your code using Babel. This plugin allows you to add new "root" directories that contain your modules. It also allows you to setup a custom alias for directories, specific files, or even other npm modules.

Description

This plugin can simplify the require/import paths in your project. For example, instead of using complex relative paths like ../../../../utils/my-utils, you can write utils/my-utils. It will allow you to work faster since you won't need to calculate how many levels of directory you have to go up before accessing the file.

// Use this:
import MyUtilFn from 'utils/MyUtilFn';
// Instead of that:
import MyUtilFn from '../../../../utils/MyUtilFn';

// And it also work with require calls
// Use this:
const MyUtilFn = require('utils/MyUtilFn');
// Instead of that:
const MyUtilFn = require('../../../../utils/MyUtilFn');

Usage

Install the plugin

$ npm install --save-dev babel-plugin-module-resolver

Specify the plugin in your .babelrc with the custom root or alias. Here's an example:

{
  "plugins": [
    ["module-resolver", {
      "root": ["./src"],
      "alias": {
        "test": "./test",
        "underscore": "lodash"
      }
    }]
  ]
}

Are you a plugin author (e.g. IDE integration)? We have documented the exposed functions for use in your plugins!

Options

• root: A string or an array of root directories. Specify the paths or a glob path (eg. ./src/**/components)
• alias: A map of alias. You can also alias node_modules dependencies, not just local files.
• extensions: An array of extensions used in the resolver. Override the default extensions (['.js', '.jsx', '.es', '.es6', '.mjs']).
• cwd: By default, the working directory is the one used for the resolver, but you can override it for your project.
  • The custom value babelrc will make the plugin look for the closest babelrc configuration based on the file to parse.
  • The custom value packagejson will make the plugin look for the closest package.json based on the file to parse.
• transformFunctions: Array of functions and methods that will have their first argument transformed. By default those methods are: require, require.resolve, System.import, jest.genMockFromModule, jest.mock, jest.unmock, jest.doMock, jest.dontMock.
• resolvePath(sourcePath, currentFile, opts): A function that is called for each path in the file. By default module-resolver is using an internal function, exposed like so: import { resolvePath } from 'babel-plugin-module-resolver'. The opts argument is the options object that is passed through the Babel config.

Regular expression alias

It is possible to specify an alias using a regular expression. To do that, either start an alias with '^' or end it with '$':

{
  "plugins": [
    ["module-resolver", {
      "alias": {
        "^@namespace/foo-(.+)": "packages/\\1"
      }
    }]
  ]
}

Using the config from this example '@namespace/foo-bar' will become 'packages/bar'.

You can reference the n-th matched group with '\\n' ('\\0' refers to the whole matched path).

To use the backslash character (\) just escape it like so: '\\\\' (double escape is needed because of JSON already using \ for escaping).

ESLint plugin

If you're using ESLint, you should use eslint-plugin-import, and eslint-import-resolver-babel-module to remove falsy unresolved modules.

Usage with React Native

To let the packager resolve the right module for each platform, you have to add the .ios.jsand .android.js extensions :

{
  "plugins": [
    [
      "module-resolver",
      {
        "root": ["./src"],
        "extensions": [".js", ".ios.js", ".android.js"]
      }
    ]
  ]
}

Usage with Flow

To allow Flow to find your modules, add configuration options to .flowconfig.

For example, a React component is located at src/components/Component.js

// Before
import '../../src/components/Component';

// After - Flow cannot find this now
import 'components/Component';

Instruct Flow where to resolve modules from:

# .flowconfig

[options]
module.system.node.resolve_dirname=node_modules
module.system.node.resolve_dirname=src

Be sure to add any sub-directories if you refer to files further down the directory tree:

// Located at src/store/actions
import 'actions/User'

module.system.node.resolve_dirname=src/store

Or you may use name_mapper option for manual listing (tested with Flow 0.45):

# .flowconfig

[options]
; Be careful with escaping characters in regexp
- module.name_mapper='^app\/(.*)$' -> '<PROJECT_ROOT>/app/\1' # does not work
+ module.name_mapper='^app\/\(.*\)$' -> '<PROJECT_ROOT>/app/\1' # work as expected

; Other modules
module.name_mapper='^i18n\/\(.*\)$' -> '<PROJECT_ROOT>/i18n/\1'
module.name_mapper='^schema\/\(.*\)$' -> '<PROJECT_ROOT>/schema/\1'
module.name_mapper='^mongoose-elasticsearch-xp\(.*\)$' -> '<PROJECT_ROOT>/lib/mongoose-elasticsearch-xp\1'

More configuration options are located in the Flow documentation

Editors autocompletion

• Atom: Uses atom-autocomplete-modules and enable the babel-plugin-module-resolver option.
• IntelliJ/WebStorm: You can add custom resources root directories, make sure it matches what you have in this plugin.

For plugin authors

Aside from the main export, which is the plugin itself as needed by Babel, there is a function used internally that is exposed:

import { resolvePath } from 'babel-plugin-module-resolver';

// `opts` are the options as passed to the Babel config (should have keys like "root", "alias", etc.)
const realPath = resolvePath(sourcePath, currentFile, opts);

For each path in the file you can use resolvePath to get the same path that module-resolver will output.

currentFile can be either a relative path (will be resolved with respect to the CWD, not opts.cwd), or an absolute path.

License

MIT, see LICENSE.md for details.