index.js

'use strict';

const path = require('path');

const localResolve = module.constructor._findPath;
const defaultExtension = ['.js', 'jsx', '.json'];

function findConfiguredPath(modulePath, alias) {
	const __pathes = modulePath.split('/');
	let aliasPath = null;

	if (__pathes.length === 1) {
		aliasPath = alias[__pathes[0]] || alias[__pathes[0] + '$'];
	} else {
		aliasPath = alias[__pathes[0]];
	}
	return aliasPath;
}

function fileWithExtension(path, extensions) {
	return extensions.some(ext => path.endsWith(ext));
}
exports.interfaceVersion = 2;

exports.resolve = function(modulePath, sourceFile, config) {
	if (config && config.resolve && config.resolve.alias) {
		const __pathes = modulePath.split('/');

		const aliasPath = findConfiguredPath(modulePath, config.resolve.alias);

		if (aliasPath) {
			let filename = null;

			if (fileWithExtension(aliasPath, defaultExtension)) {
				filename = localResolve(aliasPath, []);
			} else {
				const filePath = aliasPath.startsWith('.')
					? path.join(__dirname, aliasPath, ...__pathes.slice(1))
					: path.join(aliasPath, ...__pathes.slice(1));
				filename = localResolve(filePath, []);
			}
			return {
				found: !!filename,
				path: filename || null,
			};
		}
	}
	return { found: false };
};