AkashRajvanshi

function Person(firstName, lastName) {
  this.first_name = firstName
  this.last_name = lastName

  this.displayName = function () {
    console.log(`Name: ${this.first_name} ${this.last_name}`) // Name: Akash Rajvanshi
  }
}

let person = new Person("Akash", "Rajvanshi")

AkashRajvanshi

const Person = {
  firstName: 'Akash',
  lastName: 'Rajvanshi',
  profession () {
    console.log(this) //{ firstName: "Akash", LastName: "Rajvasnhi", profession: f{} }
  }
}

Person.profession()

AkashRajvanshi

const Person = {
  name () {
    const firstName = function () {
      console.log('Akash', this)
    } // window
    firstName()
    console.log('Rajvanshi', this) // Rajvanshi {name: f}
  }
}

AkashRajvanshi

const Person = {
  name() {
    const firstName = _ => console.log('Akash', this) //Akash {name: f}
    firstName()
    console.log('Rajvanshi', this) //Rajvanshi {name: f}
  }
}

Person.name()

AkashRajvanshi

const button = document.querySelector('button')

button.addEventListener('click', function () {
  console.log(this) // button
})

AkashRajvanshi

function foo () {
  console.log(this.a) // 3
}

var a = 3 // because this reference the global object and here our var 'a' is global variable.
foo()

AkashRajvanshi

function foo() {
  console.log(this.a) // 2
}

const obj = {
  a: 2,
  foo // Es6 syntax of foo: foo
}

obj.foo()

AkashRajvanshi

function foo() {
  console.log(this.a) //2
}

var obj = {
  a: 2
}

foo.call(obj)

AkashRajvanshi

// Example with Normal Function
// Value of "this" in this method is overridden to 3

function foo() {
  return function (value) {
    console.log(this.value) // 3
  }
}

var obj1 = {

AkashRajvanshi

const firstName = _ => console.log('Akash', this) //Akash -> window
firstName()