Node.js - Built-in

process

process is the global object, similar to window in browser.

process.env

process.env: environment variables defined and exported in ~/.bash_profile or ~/.bashrc

process.argv

Stores commandline arguments. Try

console.log(process.argv)

from commandline

$ node test.js foo
[ 'node',
  '/path/to/test.js',
  'foo' ]

process.exit()

Exit program.

OS

Get num of CPUs:

var numCPUs = require("os").cpus().length;

JSON

JSON is exposed by V8

• JSON.stringify(object): convert object to string
• JSON.parse(string): convert string to object

To pretty print(indent by 4 spaces):

JSON.stringify(data, null, "    ");

or

JSON.stringify(data, null, 4);

Others

require, module, and exports.