Node.js

Installation

sudo pacman -Sy nodejs
sudo pacman -Sy npm

On Windows with Chocolatey, with one of the following (I am not really sure how they differ, but see also this stackoverflow answer).

choco install -y nodejs
choco install -y nodejs-lts
choco install -y nodejs.install

APT

Distributions with APT (Debian, Ubuntu, …). npm is typically required, too:

sudo apt install nodejs
sudo apt install npm

It turns out that the installed version is quite behind (as of 2023-03-04:)

$ node -v
v12.22.12

Hello World

var http = require('http');

http.createServer(
  function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.end('Hello World\n');
  }
).listen(1337, '127.0.0.1');

console.log('Server running at http://127.0.0.1:1337/');

Github repository about-node.js, path: /hello-world.js

The Hello World application can be started with

$ node hello-world.js

Using node.js as a shell

node.js can be used as a shell by typing the executable name node without a script name:

PS C:\Users\Rene> node

Exiting from the shell:

> process.exit()

Logging

Some basic logging functionality is provided by the logging module.

The logging module needs not be added with require('logging') (2020-09-23: this seems not to be the case anymore).

console.log('some text');
console.log('more text');
console.log('the end.' );

Github repository about-node.js, path: /api/console/log.js

Modules / require()

Types of modules

Built-in (core) modules (such as fs, http, …)
NPM modules: these are 3rd party modules, to be installed with npm install ….
Local modules (identified by using path specifiers as ./, ../ in their name and having on of the suffixes .js, .json, .mjs, .cjs, .wasm or .node).

require()

Modules are imported with the special purpuse function require (which is not part of the standard JavaScript API).

In order for a module to be importable with require, the module must either be

a folder with a package.json file, or
a JavaScript file

Accessing environment variables

The values of environment variables can be accessed via process.env.ENVVAR:

console.log('Home directory: ' + process.env.HOME);

Github repository about-node.js, path: /api/process/env.js

Temporary directory

The path of the temporary directory (usually /tmp on Linux) is returned by os.tmpdir() or os.tmpdir:

const os = require('os');
console.log('The temporary directory is: ' + os.tmpdir);

Github repository about-node.js, path: /api/os/tmpdir.js

TODO

Yarn

Yarn, yet another resource navigator, is an alternative package manager to npm.

Unlike npm, Yarn does not come pre-installed with Node.js and needs therefore to be installed separately:

npm install yarn -g

nvm

nvm is a version manager for node.js which works on POSIX compliant shells (including WSL).

nvm is installed with the following command:

curl https://raw.githubusercontent.com/creationix/nvm/master/install.sh | bash

The following command installes version 19 to ~/.nvm/versions/node/v19.…/bin/node:

nvm install 19