JAVASCRIPT

JavaScript Objects

const objectName = {
  member1Name: member1Value,
  member2Name: member2Value,
  member3Name: member3Value
};

js objects

// To make an object literal:
const dog = {
    name: "Rusty",
    breed: "unknown",
    isAlive: false,
    age: 7
}
// All keys will be turned into strings!

// To retrieve a value:
dog.age; //7
dog["age"]; //7

//updating values
dog.breed = "mutt";
dog["age"] = 8;

JavaScript Objects

let car = "Fiat";

ways of defining object js

1) Object Literal
	const obj = {
    	name: "Ram",
      	age: "20"
    }
2) Constructor Function or ES6- Class
   const a = new Person("Ram", "25") //given Person is an existing function or class
3) Object.create method
	const ram = Object.create(Person); //given person is an existing object

how to create object js

function person(fname, lname, age, eyecolor){
  this.firstname = fname;
  this.lastname = lname;
  this.age = age;
  this.eyecolor = eyecolor;
}

myFather = new person("John", "Doe", 50, "blue");
document.write(myFather.firstname + " is " + myFather.age + " years old.");

javascript object

/*
An object is made of key value pairs. Keys can be strings 
(which don't require quotes), array with a string, or symbols. Values can be arrays,
objects, numbers etc
*/

let testSymbol = Symbol('item number 3')

const obj = {
	item1: 1,
    "item number 2": 2,
    testSymbol: 3,
  	['a']: 4
}

// Another way of creating an object:
const obj = new Object();
obj.name = 'John'

// To access values, you can use dot notation or bracket notation. 
// Both do the same thing, bracket notion is useful for multispace keys,
// keys with dashes, or accessing values using variables
> obj.item1
> obj['item number 2']

> let b = 'item1'
  obj[b]
  // The following would NOT work and would return undefined:
  obj.b

// Checking exsistence of keys in object:
obj.toString ----- checks values of object and whatever object inherits from
> returns true

obj.hasOwnProperty('toString') ----- checks values of object only. Do this instead of checking like: (obj.name !== undefined)
> returns false


// Short hand key assignment:
const name = 'John'
const obj2 = {
    // this is short hand that automatically sets the key to be 'name',
    // and it's value to be 'John'
	name, 
}

// Constructor objects:
function Obj(name, age){
	this.name = name
  	this.age = age
}

const person = new Obj('john', 1)

// adding functions, couple ways:
const obj = {
  	name: 'Mike',
  	number: 4421,
	sayHi: () => console.log('hi'),
  	sayBye() {
    	console.log('say bye')
    },
    // getter function to get values from object. Has different usecases, but the same as doing obj.number
  	get getNumber(){
    	return this.number
    }
    // setter function to set values in object. Has different usecases, but the same as doing obj.number = 152
    set setNumber(num){
    	this.number = num
    }
}

obj.sayHi()
obj.sayBye()
obj.getNumber //Note how it's being accessed like a standard property, and not a function
obj.setNumber //Note how it's being accessed like a standard property, and not a function

javascript objects

const someObj = {
  propName: "John"
};

function propPrefix(str) {
  const s = "prop";
  return s + str;
}

const someProp = propPrefix("Name");
console.log(someObj[someProp]);

javaScript object

var emp = {
name: "khan",
age: 23
};

object JavaScript

//create an obect of a scary housekeeper
var houseKeeper = {//the following are all properties
    name: "Moira O'Hara",//creating variables and assigning
    experienceInYears: 9,
    everBeenFired: false,
    priorJobs: ['Grand Budapest Hotel', 'The Overlook', 'Pinewood Hotel', 'Slovakian Hostel'],
    dateHired:  new Date('01/13/2022'),
    currentEmployee: true,
    dateOfTermination: new Date(0),
    reasonForTermination: '',    
};
//using dot notation to edit object
houseKeeper.everBeenFired = true;
houseKeeper.currentEmployee = false;
houseKeeper.dateOfTermination = new Date('10/3/2022');
houseKeeper.reasonForTermination = ['anger issues', 'violation of customer privacy']

//using dot notation to access object
console.log("Date of Hire : ", houseKeeper.dateHired)
console.log("House Keeper : ", houseKeeper.name)
console.log("Current Employee? : ", houseKeeper.currentEmployee)
console.log("Date of Termination : ", houseKeeper.dateOfTermination)
console.log("Reason for Termination : ", houseKeeper.reasonForTermination)

create object javascript

let voleur = {
     action     : () =>console.log ('Coup de dague fatal') ,
     crie      : ('pour la horde!!!!') ,
     coupfatal :()=> console.log ('coup dans le dos')

}

voleur.action() ;
voleur.coupfatal() ;
console.log(voleur.crie) ;

javascript object

[object Object]
Object { }
{ }

JavaScript Objects

// object
const student = {
    firstName: 'ram',
    class: 10
};

object object js

var obj = new Object();

javascript object

let person = {
    firstName: 'John',
    lastName: 'Doe'
};Code language: JavaScript (javascript)

JavaScript Object

const student = {
    firstName: 'ram',
    lastName: null,
    class: 10
};

javascript object

const obj = {
    name: "Mon contenu",
    id: 1234,
    message: "Voici mon contenu",
    author: {
        name: "John"
    },
    comments: [
        {
            id: 45,
            message: "Commentaire 1"
        },
        {
            id: 46,
            message: "Commentaire 2"
        }
    ]
};

how to write an object in javascript?

const person = {
  name: 'Nick'
};
person.name = 'John' // this will work ! person variable is not completely reassigned, but mutated
console.log(person.name) // "John"
person = "Sandra" // raises an error, because reassignment is not allowed with const declared variables

js object

'use strict';

var obj = {
  a: 10
  b:20
};

Object.defineProperty(obj, 'b', {
  get: () => {
    console.log(this.a, typeof this.a, this); // undefined 'undefined' Window {...} (or the global object)
    return this.a + 10; // represents global object 'Window', therefore 'this.a' returns 'undefined'
  }
});

js object

const person = {
    firstName: 'John',
    age: 30,
    greet() {//method
        console.log('Hi, I am ' + this.name);
    },
    age(){//method
        console.log('I am ' + this.age + ' years old');
    }
}

person.lastName = 'Doe';//add property to object

console.log(person.lastName);// output: Doe
// Calling a method
person.greet();// output: Hi, I am Doe
person.age();// output: I am 30 years old

javaScript object

var emp = {
name: "khan",
age: 23
};

javaScript object

var emp = {
name: "khan",
age: 23
};

js object

var person = {
  "name" : "Mrs. White"
};