Table of Contents Overview Timeline Install using nvm install nvm install node/npm automatic switching enable switching describe required version (.nvmrc) test Hello, world Folder structure API http Entry-point module export (module.exports) import (require) caution Network Launch Debug exit

Handful:

• asynchronous, non/blocking IO implemented in a single threaded
• "the main event loop is single-threaded but most of the I/O works run on separate threads"
• Check Deno to seeNode.js vulnerabilities

Links

• Node (french)

More here List:

• 2009: Presentation by Ryan Dahl at JSConf

Node Version Manager (NVM) allow easy version switching for:

• node;
• node package manager (npm).

Install for:

• bash
  • curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.2/install.sh | bash
  • activate auto-completion npm completion >> ~/.zshrc
• zsh
  • https://github.com/lukechilds/zsh-nvm , section "As an Oh My ZSH! custom plugin"
• upgrade: nvm upgrade

Latest:

• check who is the latest:
  • nvm ls-remote | tail
  • OR nvm ls
• install latest: nvm install node
• activate: nvm use node
• check installed (green arrow) : nvm ls

Specific (eg. 14.4.0):

• install latest: nvm install 14.4.0
• activate: nvm use 14.4.0
• check installed (green arrow) : nvm ls

Include npm:

• details
• matching here

Expect you to create a config file (.nvmrc) per repository, as nvm does not read "engine key" from package.json as for now

Configure your terminal

Use the current version: node -v > .nvmrc

Or create the .nvmrc file manually

Steps:

• restart your terminal
• list available versions and choose an old one: nvm ls
• switch to this version: nvm use <VERSION_NUMBER>
• enter the folder with .nvmrc file, you get the following message

Found '.nvmrc' with version <13.8.0>
Now using node v13.8.0 (npm v6.13.6)

Create helloWorld.js

#! /usr/bin/env node
let people = 'node';
console.log("\"Hello, world ! \" says", people);

Execute node helloWorld.js , uou'll get "Hello, world ! " says node

SO

List:

• source in src
• test:
  • unit in test
  • BDD in spec
• resources in public
  • images
  • css
  • js for client-side, not compiled

all headers are made lowercase

From here

If a standalone script, if you want to have a single entry-point

const mainFunction = function(people){
   console.log('Hello, ' + people + ' !');
}

if (require.main === module) {
   mainFunction('world');
}

Each file is a module. As each module hide its content by default (encapsulation), you should explicitly defined which element should be exposed. This is done through module's export property.

module.exports is a hook on which you can add any properties:

• function (standard & class)
• values (const / let)
• object

prototype.js

const makeAgedBrie = function (agedBrieParams) {(..)};

// export
module.exports.Item = Item;
module.exports.makeAgedBrie = makeAgedBrie;

OR (shorthand)

module.exports = {
    Item,
    makeAgedBrie
}

If using exports instead of module.exports , make sure you know what you do

Import is intended to expose another module interface into the current module, so you can call it.

prototype.test.js

// import
const {Item, makeAgedBrie} = require('./prototype');

// use
const standardItem = new Item(standardItemParams) ;

require:

• is synchronous;
• use cache : when two module use same one, its state is shared see here

Imported object behave like a singleton if:

• OS is case-sensitive (eg. Linux)
• use npm 3 or higher (since 2016)
• use same module & dependencies version

All details here

require also execute the code from the exported module.

Usually, the exported module does nothing by itself, but defining functions and exposing them in module.exports. However, the following is allowed:

• the required module execute code (if not already imported in another module, because of cache)
• the requiring module discard the returned reference

An example of starting an HTTP server here

Allow SLL connection with self-signed certificate NODE_TLS_REJECT_UNAUTHORIZED='0' node

List:

• http call

To launch an async function on node REPL, you'll need an async IIFE

const messageBus = require('./message-bus');
( async() => {messageBus.sendEmailChange({id: 0, newEmail: '[email protected]'}) })();

One-liner: ( async() => {require('./message-bus').sendEmailChange({id: 0, newEmail: '[email protected]'}) })();

To get additional informations, use `NODE_DEBUG` environment variable:

• NODE_DEBUG=* node : verbose
• NODE_DEBUG=net node : HTTP call
• NODE_DEBUG=module node : module resolution (require trace)

Node should exit after executing all functions If not, you may want to use process.exit(EXIT_CODE) to force exit

Better use this package to track what prevents node to exit