// Function example:

// - using var:

function test(){

&emsp; var a=4;

&emsp; console.log(a); //a=4

}

console.log(a); //a is not defined

// var value is not avaiable outside a function because it's function scoped.

// - using let

// In case of a function, the braces identify a block.

function test(){

&emsp; let b=6;

&emsp; console.log(b); //b=4

}

console.log(b); //b is not defined

// let value is not avaiable outside a function because it's block scoped.

// Code block example:

// - using var:

{

&emsp; var a=8;

&emsp; console.log(a); //a=8

}

console.log(a); //a=8

// var value is also avaiable outside a block because it's function scoped not block scoped.

// - using let:

{

&emsp; let b=10;

&emsp; console.log(b); //b=10

}

console.log(b); //b is not defined

// let value is only avaiable inside a block because it's block scoped.

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For Topic: DevTools