Skip to content

Latest commit

 

History

History
122 lines (80 loc) · 1.72 KB

E03 - Hoisting in JavaScript (variables & functions).md

File metadata and controls

122 lines (80 loc) · 1.72 KB

Episode 3: Hoisting in JavaScript 🔥(variables & functions)

Let us understand the concept by the following examples.

// code example 1

var x = 7;
function getName(){
    console.log("Namaste JavaScript");
}

getName();
console.log(x);

Output:

Namaste JavaScript

7

// code example 2

getName();
console.log(x);

var x = 7;
function getName(){
    console.log("Namaste JavaScript");
}

Output:

Namaste JavaScript

undefined

// code example 3

getName();
console.log(x);

function getName(){
    console.log("Namaste JavaScript");
}

Output:

Namaste JavaScript

Error: x is not defined

Hoisting is a concept which enables us to extract values of variables and functions even before defining them.

// code example 4

function getName(){
    console.log("Namaste JavaScript");
}

console.log(getName)

Output:

f getName(){ console.log("Namaste JavaScript); }

// code example 5

getName();
console.log(x);
console.log(getName)

function getName(){
    console.log("Namaste JavaScript");
}

Output:

Namaste JavaScript

undefined

f getName(){ console.log("Namaste JavaScript); }

// code example 6

console.log(getName)

var getName = function () {
    console.log("Namaste JavaScript");
}

var getName = () => {
    console.log("Namaste JavaScript");
}

Output:

undefined

REASON OF WEIRDNESS

  • The answer lies in the Global Exection Context. In the memory phase, the variables will be initialized as undefined and functions will get the whole function code in their memory.

  • This is the reason why we are getting these outputs.