JavaScript - const,let and var Quiz

Topics: JavaScript const, let, and var

JavaScript - const,let and var

In JavaScript, variables can be declared using three different methods: var, let, and const.

4 mins read

Block scope

Global scope

Function scope

var

let

const

All of them

null

undefined

const x = 10;
 
 if (true) {
  const x = 20;
  console.log(x);
 }
 console.log(x);

10 20

20 10

undefined

ReferenceError: x is not defined

let

const

Both let and const

It throws a ReferenceError.

It returns `undefined`.

It gives the value assigned to it.

It depends on the context.

var

let

const

All of them are equally recommended.

Both `var` and `let` variables are hoisted to the top of their scope.

`var` variables are hoisted with the value `undefined`, while `let` variables are not initialized during hoisting.

`var` variables are not hoisted, while `let` variables are hoisted to the top of their scope.

There is no difference in hoisting behavior between `var` and `let`.