Node.js

An Introduction to Node.js

By me, Kyle Mitofsky, a developer

---

NodeJS

... an asynchronous, event-driven, JavaScript runtime, designed to build scalable network applications

---

Write an App

Language
&
Runtime

Client and Server

---

Functions 101

• ECMAScript 20??
• Callbacks
• Promises
• Async / Await

Function Declaration

// function declaration
function SayHi (name) {
    console.log(`Hi: ${name}`)
}

// function expression / assignment
let SayHey = function (name) {
    console.log(`Hey: ${name}`)
}

// arrow function / lambda
SayHello (name) => {
    console.log(`Hello: ${name}`)
}

Note: func delcarations -> are hoisted to the top of the scope (immediately available).
arrow func -> lecical this (defined by outer scope)

Functions Invocation

SayHi('kyle');

SayHi.Call(this, 'kyle');    // C for Comma

SayHi.Apply(this, ['kyle']); // A for Array

Return Result

function Multiply(a, b) {
    return a * b
}
// invoke

let result = Multiply(2,5)
console.log(result)

Callback w/ Result

function Multiply(a, b, callback) {
    callback(a * b) // pretend this took a while
}

// invoke w/ anonymous function
Multiply(2,5, (result) => {
    console.log(result)
})

Promises

// wrap a callback in a promise
function MultiplyPromise(a,b) {
    return new Promise((resolve) => {
        Multiply(a, b, (result) => {
            // resolve promise from in callback
            resolve(result)
        });
    });
}

Promise with Callback

let multPromise = MultiplyPromise(a,b)

multPromise.then(result => {
  console.log(result)
})

Promise with Async / Await

(async function(){

    let result = await MultiplyPromise(a,b)
    console.log(result)

})()

---

Node vs .NET

	.NET	Node
Language	C# / VB / F#	JS / TS
Runtime	MSIL	V8
Platform	Win, Mac, Linux	Win, Mac, Linux
Packages	Nuget	npm

---

Demo Time

---

Resources

• NodeJs Calendar Quickstart