Node.js Snippets

Environment Variables & Debugging

NODE_ENV=production node index.js
NODE_DEBUG=http node index.js

• NODE_ENV=production: Sets the environment to production when running the app.
• NODE_DEBUG=http: Enables debug logging for HTTP-related code.

process.argv

node index.js dumpall junha

console.log(process.argv);
// Output:
// [0]: '/path/to/node'
// [1]: '/path/to/script.js'
// [2]: 'dumpall'
// [3]: 'junha'

• process.argv is an array containing the command-line arguments passed when the Node.js process is launched.
  • [0]: Full path to the Node executable.
  • [1]: Full path to the script being executed.
  • [2] and onward: Additional command-line arguments.

Serving Static Files with Express

app.use('/public', express.static(__dirname + '/public'));
// This middleware handles requests to the '/public' route.
// It serves static files from the directory located at __dirname + '/public'.

• /public: The URL path where static files will be served.
• express.static: Middleware to serve static files, like HTML, CSS, JavaScript, etc.
• __dirname: Represents the absolute path of the directory containing the executing script.

Module Systems: CommonJS vs ES Modules

CommonJS

console.log(__filename); // Example: /Users/username/project/example.js
console.log(__dirname);  // Example: /Users/username/project

• __filename: The absolute path of the currently executing file.
• __dirname: The directory name of the currently executing script.

ES Modules

import { fileURLToPath } from 'url';
import { dirname } from 'path';

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

console.log(__filename); // Similar to CommonJS, absolute path to the file.
console.log(__dirname);  // Similar to CommonJS, directory of the current file.

• fileURLToPath(import.meta.url): Converts the import.meta.url (file URL) into a file path.
• dirname(__filename): Retrieves the directory name of the current module.