Block Scope in JavaScript

{ 
    //this is a block
} 

    block is used to combine multiple JavaScript statement in one group. block is known as compound statement. 

    so this group of multiple statements can be used in a placed where JavaScript expected a single statement. Ex.

let x = 0
if(x == 2){
    x = x + 1;
    console.log('it is not 0');
}

like this, all statements are in group with it's {}. because if expects single statement like if(x == 2) true but we want to more statement so we need block. 

    Everyone says let and const are block scope. but Why?

let’s declare three variable and see what’s happening inside it?

var a = 1;
let b = 2;
const c = 3;

    This let b and let c is gone in block section and var a is goes to Global section. means let b and let c are store but in different in place. and we packed all this variable in block means inside {} so can we access this let and const variable in outside the block? obviously no! that’s why let and const are block scope.

{
    var a = 10;
    let b = 100;
    const c = 1000;
}
console.log(a)

we can access a bcz. this variable declare using var is a global scope.