AkashRajvanshi

//Example of Properties, keys & Values
let user = { // An object
  name: 'akash', // 'name' is a key: 'akash' is a value
  age: 22
};

AkashRajvanshi

const fullName = {
  first: 'Akash',
  last: 'Rajvanshi'
};

console.log(fullName.first) // Akash
// In this code, we create an object via an object literal, which starts with a curly brace and end with a curly brace {...}. 
// Inside it, we have propety: {Key = first, last} and {value = Akash, Rajvanshi}

AkashRajvanshi

const user = {
  firstName: 'Akash',
  lastName: 'Rajvanshi',
  fullname: function () { //method
    return `${this.firstName} ${this.lastName}`
  }
};

console.log(user.fullname()) //Akash Rajvanshi
console.log(user.firstName) //Akash

AkashRajvanshi

console.log(user.fullname()) // call method fullname
// Akash Rajvanshi

AkashRajvanshi

user.firstName = 'Abha' // Set property 'firstName'
console.log(user.firstName) // Abha

AkashRajvanshi

delete user.firstName
console.log(user.firstName) //undefined 
console.log(Object.keys(user) // [ 'lastName', 'fullname' ]

// But if we set a property to 'undefined', the property still exits and the object still contains its key.

user.firstName = undefined
console.log(Object.keys(user)) // [ 'lastName', 'fullname', 'firstName' ]

AkashRajvanshi

Object.defineProperty(user, 'canBeDeleted', {
  value: 123,
  configurable: true
});
Object.defineProperty(user, 'cannotBeDeleted', {
  value: 456,
  configurable: false
});

console.log(delete user.cannotBeDeleted) // false

AkashRajvanshi

const fullName = {
  first: 'Akash',
  last: 'Rajvanshi',
  get full() {
    return `${this.first} ${this.last}`
  }
};

console.log(fullName.full) // Akash Rajvanshi

AkashRajvanshi

const fullName = {
  first: 'Akash',
  last: 'Rajvanshi',
  set full(name) {
    const parts = name.split(' ')
    this.first = parts[0]
    this.last = parts[1]
  }
};

AkashRajvanshi

let fullName = {
	first: 'Akash',
	last: 'Rajvanshi'
};

fullName = {...fullName, age: 22}
console.log(fullName) // { first: 'Akash', last: 'Rajvanshi', age: 22 }

// Extra Features 
// 1. Changing content of an object