Javascript - Objects

Leon Noel

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Agenda

• Questions? 
• Let's Talk -  #100Devs
• Review - Functions && Loops
• Review - Arrays
• Learn - Objects
• Learn - Basic APIs
• Homework - Objects Reading

Questions

About last class or life

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Programming

A computer will do what you tell it to do.

What is a program?

A program is a set of instructions that you write to tell a computer what to do

What is a programming?

Programming is the task of writing those instructions in a language that the computer can understand.

JAVASCRIPT

Has a specific 'Syntax'

Syntax: "Spelling and grammar" rules of a programming language.

Variables

Conditional Syntax

if(condition is true) {
  //Do this cool stuff
}else if(condition is true){
  //Do this other cool stuff
}else{
  //Default cool stuff
}

🚨 DANGER 🚨

Assignment vs. Comparison

Multiple Conditions

if (name === "Leon" && status === "Ballin"){
 //Wink at camera
}

Multiple Conditions

if (day === "Saturday" || day === "Sunday"){
  //It is the weekend
}

Functions

What are functions?

Functions

• Functions are simple sets of instructions!
• Functions are reusable
• Functions perform one action as a best practice
• They form the basic "building blocks" of a program

Functions

function name(parameters){
  //body
}

//call
name(arguments)

Functions

function yell(word){
  alert(word)
}


yell("HELLO")

Loops

What are loops?

Loops

• Repeat an action some number of times!
• Three main types of loops in Javascript
• For, while, and do while loops
• Each type offers a different way to determine the start and end points of a loop

Loops - For

for (let i = 1; i < 5; i++) {
  console.log(i)
}

Loops - While

let count = 0 

while(count < 5){
  console.log(count)
  count++
}

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Arrays

What are arrays?

Toasters

Arrays

• A data structure to store ordered collections!
• Array elements are numbered starting with zero
• Arrays have many methods to manage the order of elements
• Can be created by a constructor or literal notation

Declaring Arrays

let newArr = new Array()

Array Constructor

Declaring Arrays

let newArr = []

Literal Notation

Declaring Arrays

newArr = ['Zebra',true,21]

Array Indexing

Array Indexing

newArr = ['Zebra',,true,21]

console.log( newArr[0] )  //Zebra
console.log( newArr[1] )  //undefined
console.log( newArr[2] )  //true
console.log( newArr[3] )  //21

Elements can be accessed by their index numbers

Array Indexing

newArr = ['Zebra',,true,21]

newArr[1] = 'Bob'

console.log( newArr )  

// ['Zebra','Bob',true,21]

Elements can be updated by using the index at that position

Array Indexing

let cars = ['Honda', 'Toyota', 'Ford', 'Tesla']
let nums = [1,2,3]
cars = nums
console.log( cars ) //[1,2,3]

You can overwrite whole arrays by assigning an array to a different array

Array Length

console.log( newArr.length ) //4

How do you determine how many elements are in your array?

Array Iteration

let bestColors = ['green','blue','yellow','black']

for(let i = 0; i < bestColors.length;i++){
  console.log( bestColors[i] )
}

Iterates through an array passing in the value and index of each element 

Array Iteration

let bestColors = ['green','blue','yellow','black']

bestColors.forEach((x,i)=> console.log(x))

Iterates through an array passing in the value and index of each element 

Other Arrays Methods

let bestRappers2020 = ['6ix9ine','Polo G','6ix9ine']

let removed = bestRappers2020.shift()

console.log( bestRappers2020 ) // ['Polo G', '6ix9ine']

Remove item from the beginning of an Array

Other Arrays Methods

let bestRappers2020 = ['Polo G','6ix9ine']

let removedAgain = bestRappers2020.pop()

console.log( bestRappers2020 ) // ['Polo G']

Remove item from the end of an Array

Other Arrays Methods

let bestRappers2020 = ['Polo G']

let removed = bestRappers2020.unshift('Dylan')

console.log( bestRappers2020 ) // ['Dylan','Polo G']

Add item to the beginning of an Array

Other Arrays Methods

let bestRappers2020 = ['Dylan','Polo G']

let removed = bestRappers2020.push('Dylan')

console.log( bestRappers2020 ) // ['Dylan','Polo G','Dylan']

Add item to the end of an Array

Other Arrays Methods

let bestRappers2020 = ['Dylan','Polo G','Dylan']

let bestRappersAllTime = bestRappers2020.map(x => 'Dylan')

bestRappersAllTime.unshift('Dylan')
  
bestRappersAllTime.push('Dylan')

console.log( bestRappersAllTime ) 

// ['Dylan','Dylan','Dylan', 'Dylan', 'Dylan']

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Objects

What are objects?

Objects

• Objects are a collection of variables and functions!
• Objects represent the attributes and behavior of something used in a program
• Object variables are called properties and object functions are called methods
• Objects store "keyed" collections

Think of a physical object

What are it's attributes and behaviors? 

How about a stopwatch

What are its attributes and behaviors? 

Stopwatch Object

• Properties (attributes):
  Might contain a variable to represent hours, another to represent minutes, and another to represent seconds. 

 

 

• Methods (behaviors):
  Might also contain functions that manipulate those values, such as "start ()" and "stop ()".

Stopwatch Object

let stopwatch = {}

stopwatch.currentTime = 12

stopwatch.tellTime = function(time){
  console.log(`The current time is ${time}.`)
}

stopwatch.tellTime(stopwatch.currentTime)

Let's Code

Objects - ZEO

Objects

What if we want to make

a lot of objects?

How much money you got? How many problems you got? How many people done doubted you? Left you out to rot?

Car Factory?

Constructors then Classes

Car Factory

Constructor

function MakeCar(carMake,carModel,carColor,numOfDoors){
  this.make = carMake
  this.model = carModel
  this.color = carColor
  this.doors = numOfDoors
  this.honk = function(){
    alert('BEEP BEEP FUCKER')
  }
  this.lock = function(){
    alert(`Locked ${this.doors} doors!`)
  }
}

let hondaCivic = new MakeCar('Honda','Civic','Silver', 4)

let teslaRoadster = new MakeCar('Tesla','Roadster', 'Red', 2)

Car Factory

We forgot enable bluetooth! 

let teslaRoadster = new MakeCar('Tesla','Roadster', 'Red', 2)

console.log( teslaRoadster.bluetooth )  //undefined

MakeCar.prototype.bluetooth = true

console.log( teslaRoadster.bluetooth ) //true 

A prototype is another object that is used as a fallback source of properties

Car Factory

Why does .toString() work?!?

let teslaRoadster = new MakeCar('Tesla','Roadster', 'Red', 2)

console.log( teslaRoadster.doors.toString() )  // "2" not 2

A prototype is another object that is used as a fallback source of properties

Let's Code

Objects - Street Fighter

Car Factory

Look Ma! New syntax!

class MakeCar{
  constructor(carMake,carModel,carColor,numOfDoors){
    this.make = carMake
    this.model = carModel
    this.color = carColor
    this.doors = numOfDoors
  }
  honk(){
    alert('BEEP BEEP FUCKER')
  }
  lock(){
    alert(`Locked ${this.doors} doors!`)
  }
}

let hondaCivic = new MakeCar('Honda','Civic','Silver', 4)

let teslaRoadster = new MakeCar('Tesla','Roadster', 'Red', 2)

Classes are like templates for objects!

APIs

What are APIs?

APIs

• A simple interface for some complex action!
• Think of a restaurant menu! Remember those...
• Lets one thing communicate with another thing without having to know how things are implemented.

APIs

APIs

Fetch Fido, Fetch!

fetch("https://dog.ceo/api/breeds/image/random")
    .then(res => res.json()) // parse response as JSON
    .then(data => {
      console.log(data)
    })
    .catch(err => {
        console.log(`error ${err}`)
    });

API returns a JSON object that we can use within our apps

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APIs

Stop trying to make Fetch happen!

fetch(url)
    .then(res => res.json()) // parse response as JSON
    .then(data => {
      console.log(data)
    })
    .catch(err => {
        console.log(`error ${err}`)
    });

Some APIs need Query Parameters to return the correct data

const url = 'https://www.thecocktaildb.com/api/json/v1/1/search.php?s=margarita'

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Homework