# babel-plugin-alias-modules

> A Babel plugin to rewrite aliased require() calls.

## Configuration

The plugin can be configured using [.npmbundlerrc global config section](https://github.com/liferay/liferay-frontend-projects/tree/master/maintenance/projects/js-toolkit/docs/.npmbundlerrc-file-reference.md#config) or in the plugin configuration itself.

In both cases the structure is the same:

```json
{
	"resolve": {
		"aliasFields": ["browser"]
	}
}
```

This resembles webpack's [resolve.aliasFields](https://webpack.js.org/configuration/resolve/#resolvealiasfields) which serves the same purpose.

Normally global config is preferred, but you can leverage plugin configuration when you need different alias fields for different packages.

The default value for `resolve.aliasFields` is `['browser']` as in webpack.

Note that this plugin used to look for `unpkg` and `jsdelivr` fields too, but it caused problems (see https://github.com/liferay/liferay-js-toolkit/issues/365 for more information).

## Technical Details

This plugin scans `package.json` for fields defined in `resolve.aliasFields` and redirects `require()`s for aliased modules.

This plugin only does one part of the whole implementation of the aliases. Aliases implementation have two parts:

1.  They redirect existing modules or provide virtual ones when seen from the outside, from another package.

2.  They make local requires divert to a different target.

This plugin does only the second part. The first one is performed by [liferay-npm-bundler-plugin-replace-browser-modules](https://github.com/liferay/liferay-frontend-projects/tree/master/maintenance/projects/js-toolkit/packages/liferay-npm-bundler-plugin-replace-browser-modules).

Please read the [`browser` field specification](https://github.com/defunctzombie/package-browser-field-spec) for more information.