process & env

The process object

process is a global object that gives your program access to the running Node.js process. It is available everywhere — no import required.

The most commonly used properties are:

Property / Method	What it gives you
`process.argv`	Array of command-line arguments
`process.env`	Object of environment variables
`process.cwd()`	Current working directory string
`process.exit(code)`	Terminate the process with an exit code
`process.platform`	OS platform string (`'linux'`, `'darwin'`, `'win32'`)
`process.version`	Node.js version string (e.g. `'v20.11.0'`)

process.argv — command-line arguments

process.argv is always an array. The first two elements are fixed:

argv[0] — path to the node binary
argv[1] — path to the script being run
argv[2] onwards — your actual arguments

Node.js

// Run as: node index.js hello world
// argv[0] = node binary path
// argv[1] = script path
// argv[2+] = your arguments

var args = process.argv.slice(2);
console.log('All argv:', process.argv);
console.log('User args only:', args);
console.log('Arg count:', args.length);

Needs the Node.js runtime — open in StackBlitz to run.

process.env — environment variables

process.env is a plain object whose keys and values are strings. It is populated from the shell environment at process startup.

Node.js

// Read a variable (returns undefined if not set)
var nodeEnv = process.env.NODE_ENV;
console.log('NODE_ENV:', nodeEnv);

// Provide a default with the || operator
var port = process.env.PORT || '3000';
console.log('PORT:', port);

// All env keys
var keys = Object.keys(process.env);
console.log('Total env vars:', keys.length);

Needs the Node.js runtime — open in StackBlitz to run.

process.cwd() and process.platform

Node.js

// Current working directory — where the process was started from
console.log('cwd:', process.cwd());

// Platform — useful for platform-specific path handling
console.log('platform:', process.platform);

// Node.js version
console.log('version:', process.version);

// Architecture
console.log('arch:', process.arch);

Needs the Node.js runtime — open in StackBlitz to run.

process.exit()

process.exit(code) terminates the process immediately. By convention:

Exit code 0 means success.
Any non-zero code (typically 1) means failure.

// Example: exit with error if a required env var is missing
if (!process.env.DATABASE_URL) {
  console.error('ERROR: DATABASE_URL is required');
  process.exit(1);
}

Calling process.exit() is a hard stop — finally blocks still run, but pending async callbacks do not. For a graceful shutdown, prefer draining the server first (e.g., server.close()), then letting the event loop exit naturally.