What Is Var, Let, And Const Keyword In Javascript

In JavaScript, developers can declare a variable using 3 keywords.

1. var

var myname='xxx';
console.log(myname); // xxx
var myname='yyy'; // yyy
console.log(myname);

2. let

let yourName='xxx';
console.log(yourName); // xxx
let yourName='yyy'; // Error
yourName = 'zzz' // zzz
console.log(yourName);

3. const

Re-assigning is not allowed.
Cannot be declared without initialization.
Declaring a variable name with the same is also not allowed.
The scope of the const keyword is also block scope.
It cannot be accessed without initialization, as it cannot be declared without initialization.

const testName;  // Error 
const testNames = 'xyz';
const testNames = 'zyx'; // Error
testNames = 'zyxx'; // Error