CommonJS is a way of exporting and import modules.

It only works in Node.js as far as I know. i.e. It does not work in the browser or in Deno.

The syntax uses module.exports to export and require to import a module.

Note this is an old style the newer ES Modules syntax is preferred over this style.

Import installed package

const request = require('request');

Local modules

Named exports

Create a variable, function or class. Then at the end of the script typically you export it.

  • foo.js 
      function foo() {
    console.log("Hello");
  }

  exports.foo = foo;

  // Or
  module.exports.foo = foo;

  // Shorthand.
  module.exports = {
    foo
  }

Now import objects by name.

const { bar } = require('./foo')

For multiple objects.

const { bar, bazz } = require('./foo')

Or, the less common form:

const bar = require('./foo').bar;

Default exports

  • foo.js 
      function foo() {
    console.log("Hello");
  }

  module.exports = 'foo';

Import the default object from a module with any name you want.

const foo = require('./foo');