@genesiscommunitysuccess/analyzer-import-alias-plugin

The Genesis Global Community Success initiative is committed to open-sourcing select technologies that we believe the open-source community would benefit from.

Analyzer Import Alias Plugin

This plugin allows you to work around the limitations of import aliasing with the AST that the analyzer uses. Consider the following pattern which you might use if you are using a design system and system of components:

// Imported Button class is a custom element.
import { Button as LibButton } from 'my-library';

// Exported Button has extra styling applied to fit your design system.
export class Button extends LibButton { }

This allows you to apply your custom styling to the library button and export with the same name, and then the consumers of your library can swap the import to get your styling. However, this has a problem...

The AST parser that powers the analyzer will be looking for a class named LibButton in your library dependencies when working out the inheritance tree of your class Button, but because the class is actually called Button in the library, the inheritance tree is broken. This means in your manifest that any members that your Button class inherits from the my-library class (or higher in the inheritance chain) will be lost on the manifest.

This plugin will allow you to fix this issue.

Usage

Installation

Install this package as a dev dependency in the same project that you're using the custom elements manifest analyzer.

npm i @genesiscommunitysuccess/analyzer-import-alias-plugin --save-dev

You then need to apply this plugin in the plugins settings in your custom-elements-manifest.config.mjs, see here.

Configuration

Adding the plugin to the plugins array in the manifest config will not accomplish anything by itself, you must also configure the way the plugin handles the name aliases. You can add a configuration for each npm package such as the following.

import aliasPlugin from '@genesiscommunitysuccess/analyzer-import-alias-plugin';

export default {
    dependencies: true,
    plugins: [
        aliasPlugin({
            'my-library': {
                '*': (name) => name.replace('Lib','')
            }
        })
    ]
}

This will effectively treat any imported superclass from my-library as without the Lib prefix, so in the first example in the readme the local Button class will be correctly inheriting from the package Button class.

The shape of the catch-all function defined as * is (name: string) => string so you may perform more complicated logic than the above example to mutate the names. If you don't want to change a name you should return the input name.

There is also an option to set specific replacements for names such as the following:

aliasPlugin({
    'my-library': {
        '*': (name) => name.replace('Lib', ''),
        LibButton: 'MyButton',
        LibCheckbox: (name) => name.replace('Lib', 'My'),
    }
})

When using this above configuration, the LibButton superclass inheritance will be treated as MyButton. Important, any explicit definition will take precedence over the catch-all * function.

For completeness, you may define as many library imports as you wish.

aliasPlugin({
    'my-library': { 
        LibButton: 'MyButton'
    },
    'another-library': {
        '*': (name) => name.replace('Another', ''),
    }
})