env-checker-strict

Ever crashed your server on a weekend due to a missing environment variable? env-checker-strict is a strict and developer-friendly environment variable checker that ensures all required env vars are validated before your app runs. Add the env reference to version control, and catch issues in production — not during your downtime.

🚀 Why use this?

Managing environment variables in large codebases can be error-prone:

• Missing env vars crash the app only during runtime ⚠️
• You don't get autocomplete or type checking 🧠
• Keeping track of all required keys is messy 📝

env-checker-strict solves these with a CLI that auto-generates a checkEnvAndThrowError() function and a typed ENVS accessor.

✨ Features

• ✅ Throws on missing env vars at startup
• 🧠 Generates ENVS object with keys for autocomplete and type safety
• ⚙️ Supports both JavaScript and TypeScript
• 🧪 Fully customizable CLI: skip keys, comment block, output file path
• 📄 Auto-detects and parses .env file
• 🔌 Auto injects required import and function call to entry file (optional with --inject flag) see CLI Options

📦 Installation

npm install -D env-checker-strict

For global CLI usage:

npm install -g env-checker-strict

🧑‍💻 CLI Usage

env-checker-strict --input .env --output env_checker.js --skip "SECRET,API_KEY" --ts

CLI Options

| Option | Alias | Description | Default | |---------------|-------|-----------------------------------------------------------------------------------------------|--------------------| | --input | -i | Path to .env file | .env | | --output | -o | Output file path for the generated checker | env_checker.js | | --skip | -s | Comma-separated list of env keys to skip from validation | (none) | | --comment | -c | Add a reminder comment at the top of .env to run env-checker-strict | true | | --ts | | Generate TypeScript output instead of JavaScript | false | | --inject | | Inject checkEnvAndThrowError() into the entry file. Optionally pass a path to the entry file | Read from package.json > main |

🔧 Example

Given .env

JWT_SECRET=supersecure
DB_HOST=localhost
DB_USER=root
DB_PASSWORD=password
API_KEY=

CLI Run

env-checker-strict -i .env -o env_checker.ts --ts -s API_KEY

Output: env_checker.ts

// Auto-generated by env-checker-strict
// ⚠️ Do not modify manually

export const ENV_LIST: string[] = [
  'JWT_SECRET',
  'DB_HOST',
  'DB_USER',
  'DB_PASSWORD'
];

export interface ENVS {
  JWT_SECRET: string;
  DB_HOST: string;
  DB_USER: string;
  DB_PASSWORD: string;
}

export const ENVS: ENVS = {
  JWT_SECRET: process.env.JWT_SECRET as string,
  DB_HOST: process.env.DB_HOST as string,
  DB_USER: process.env.DB_USER as string,
  DB_PASSWORD: process.env.DB_PASSWORD as string
};

export const checkEnvAndThrowError = (): void => {
  for (const env of ENV_LIST) {
    if (!process.env[env]) {
      const message =
        `[ENV ERROR] Missing required environment variable: ${env}\n` +
        `➡️  Make sure '${env}' is defined in your .env file.\n` +
        `📄 Location: ${import.meta.url || 'env-checker.ts'}`;

      console.error(message);
      throw new Error(message);
    }
  }
};

✅ How to Use in Project

JavaScript (index.js)

const { checkEnvAndThrowError, ENVS } = require('./env_checker');
checkEnvAndThrowError();
console.log(ENVS.JWT_SECRET); // Autocomplete for all env vars

TypeScript (main.ts)

import { checkEnvAndThrowError, ENVS } from './env_checker';
checkEnvAndThrowError();
console.log(ENVS.JWT_SECRET); // Fully typed access

💡 Tips

• Always run the CLI after updating your .env file.
• Keep the generated file in source control (optional, but helpful).
• Use the ENVS object across your app instead of process.env.

🪪 License

MIT — safe, free, and open.

Made with ❤️ to make your environment safer and your dev experience sharper.

PRs and suggestions welcome 🙌