node_modules/eslint/lib/cli-engine/load-rules.js

/**
 * @fileoverview Module for loading rules from files and directories.
 * @author Michael Ficarra
 */

"use strict";

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const fs = require("node:fs"),
	path = require("node:path");

const rulesDirCache = {};

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

/**
 * Load all rule modules from specified directory.
 * @param {string} relativeRulesDir Path to rules directory, may be relative.
 * @param {string} cwd Current working directory
 * @returns {Object} Loaded rule modules.
 */
module.exports = function (relativeRulesDir, cwd) {
	const rulesDir = path.resolve(cwd, relativeRulesDir);

	// cache will help performance as IO operation are expensive
	if (rulesDirCache[rulesDir]) {
		return rulesDirCache[rulesDir];
	}

	const rules = Object.create(null);

	fs.readdirSync(rulesDir).forEach(file => {
		if (path.extname(file) !== ".js") {
			return;
		}
		rules[file.slice(0, -3)] = require(path.join(rulesDir, file));
	});
	rulesDirCache[rulesDir] = rules;

	return rules;
};