A TypeScript utility to safely retrieve environment variables with optional fallbacks. Ensures critical environment variables are present and throws errors early when missing. Helps prevent runtime bugs due to undefined config.

getEnv.ts

/**
 * Usage:
 * create a .env file containing the correct env names
 * export const PORT = getEnv("PORT");
 * const DB_URL = getEnv("DATABASE_URL"); // throws if not defined
 */

const getEnv = (key: string, defaultValue?: string): string => {
  const value = process.env[key] || defaultValue;
  if (value === undefined) {
    throw new Error(`Environment variable ${key} is not defined`);
  }
  return value;
};