Learning Node JS.md

NodeJS

Basics

Useful default objects in different runtimes:

• Chrome runtime on V8
  • window
  • document
  • fetch() for calling APIs
• Node runtime on V8
  • global
  • process

Non-blocking example

getUser(1, (user) => {
  console.log(user)
})

Common convention

• <function>: Non-blocking
• <function>Sync: Blocking

Commands

• npm init -y: initialise with defaults
• npm i <package>: install
• npm un <package>: uninstall
• nodemon src/app.js -e js,hbs: changes refreshed included hbs and js files

Useful global imports

• process.argv: Arguments
• __dirname: current directory
• __filename: current file

Modules

Core modules 3rd party modules Your own modules

Define all of the things we can share with other files

modules.export = <value>

Useful libraries

• chalk: Colours for terminal
• nodemon: See changes instantly nodemon app.js
• yargs: Argument processing
• request: For HTTP requests
• express: Web server
• hbs: View engine for express based on handlerbars (based on Mustache templating)
• reactive-native-cli: For building react native applications

Yargs

Automatically includes --help and --version

Better argument object with yargs.argv

Change version with yargs.version('1.0')

yargs.command({
    command: 'add',
    describe: 'Add a new note',
    builder: {
        title: {
            describe: "Note title",
            demandOption: true,
            type: 'string'
        }
    },
    handler: function (argv) {
      console.log('Adding a new note', argv.title)
    }
})

JSON processing

const book = {
    title: '12 Rules to Life',
    author: 'Jordan Peterson'
}

const bookJSON = JSON.stringify(book)
console.log(bookJSON)

const parsedData = JSON.parse(bookJSON)
console.log(parsedData.author)

Useful Array Functions

array.forEach(function)
array.filter(function)
array.find(function)

Debugging

Add debugger in your code anywhere for a breakpoint. Then, run node inspect <file> Or, go to chrome://inspect in Chrome to get a nice GUI.

Asynchronous

setTimeout(() => {
    console.log('Non-blocking. This message will display after 2 seconds')
}, 2000)

Import styles

• JavaScript modules (import/export)
• CommonJS (require/exports)

NVM

# Set default alias
nvm alias default v16.14.2

# Use based on .nvmrc
nvm use

# Use specific
nvm use 16

W/ Typscript

More information here

#!/usr/bin/env node

Sample Applications

The Complete Node.js Developer Course

• Note Taking (Fundamentals, Debugging)
• Weather (APIs)
• Task App (Promises, REST, Mongo, Security, Emails, Uploads, Testing, Sort/Page/Filter)
• Chat App (Sockets)