Reads babelrc module-resolver aliases and convert to aliases for webpack

getAliasesFromBabelModuleResolver.js

const fs = require('fs');
const path = require('path');

/**
 * Reads babelrc module-resolver aliases and convert to aliases for webpack
 *
 * @prop {string} babelrcPath - path to .babelrc
 * @return {object} - webpack alias object
 * @author maddrag0n // (https://github.com/maddrag0n)
 * @license BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause
 */
const transform = (babelrcPath) => {
	// read babelrc
	const { plugins } = JSON.parse(fs.readFileSync(babelrcPath, { encoding: 'utf8' }));

	// get moduleResolverPlugin config
	const moduleResolverPlugin = (plugins || []).filter(c => Array.isArray(c))
		.find(c => c[0].toLowerCase() === 'module-resolver') || [];

	// get alias property
	const { alias: aliasCandidate, root: rootCandidate } = (moduleResolverPlugin[1] || {});
	const alias = aliasCandidate || {};

	// normalize root config
	const root = Array.isArray(rootCandidate)
		? rootCandidate
		: [ rootCandidate || './' ];

	// flatten root config
	const rootPath = !root.length
		? ''
		: root.filter(c => Boolean(c.replace('./', '')))
			.reduce((acc, partial) => path.join(acc, partial), '');

	// resolve cwd with root config
	const cwd = path.dirname(path.resolve(babelrcPath));
	const rootDir = path.join(cwd, rootPath);

	// transform babelrc alias to webpack resolve alias
	const transformed = Object.keys(alias)
		.reduce((acc, key) => {
			const value = alias[key];

			if (value.startsWith('.')) {
				acc[key] = path.join(rootDir, value);

			} else {
				acc[key] = value;
			}

			return acc;
		}, {});

	return transformed;
};

module.exports = transform;