Script to check the existing variable names of the .env.example file matches the ones in the sibling .env.development file

env-variable-name.js

import fs from "fs";
import dotenv from "dotenv";
import { fileURLToPath } from "url";
import path from "path";

const referenceFiles = [
	".env.development",
	".env.local",
	".env.production",
	".env",
];

function fileExists(filePath) {
	try {
		return fs.existsSync(filePath);
	} catch (err) {
		return false;
	}
}

function findReferenceFile() {
	for (const file of referenceFiles) {
		if (fileExists(file)) {
			return file;
		}
	}
	return null;
}

const __filename = fileURLToPath(import.meta.url);
const dirname = path.dirname(__filename);
const rootDir = path.resolve(dirname, "../");

/**
 * @param {string} fileName just the file name + extension, no path required
 * @returns
 */
function getEnvVariables(fileName) {
	const resolvePath = path.resolve(rootDir, fileName);
	const fileContent = fs.readFileSync(resolvePath, "utf-8");
	const envConfig = dotenv.parse(fileContent);
	return Object.keys(envConfig);
}

function init() {
	try {
		const referenceFile = findReferenceFile();
		if (!referenceFile) {
			console.error(
				`Error: No reference file (${referenceFiles.join(", ")}) found.`
			);
			process.exit(1);
		}

		const referenceEnvVariables = getEnvVariables(referenceFile);
		const exampleEnvVariables = getEnvVariables(".env.example");

		const missingVariables = referenceEnvVariables.filter(
			(variable) => !exampleEnvVariables.includes(variable)
		);

		if (missingVariables.length === 0) {
			console.log(
				`All environment variables in .env.example are defined in ${referenceFile}.`
			);
		} else {
			console.error(
				`The following environment variables are missing in ${referenceFile}:`
			);
			console.error(missingVariables);
			process.exit(1); // Exit with an error code to fail the pre-push hook
		}
	} catch (error) {
		throw new Error(error);
	}
}

init();