Variables

1.Variables in JavaScript

• JavaScript variables are containers for data.

• JavaScript variables can be declared in 3 ways: var, let, const

var:

• The var keyword was used in all JavaScript code before 2015.

• It can be redeclared and reassigned anywhere in the program.

• var a = 10;
var a = 20; //redeclared
a = 30; //reassigned
console.log(a) //output:30

let:

• It can be reassigned but it cannot be redeclared in the program.

• let a = 20;
a = 30; //reassigned
let a = 10; //redeclared(error)
console.log(a) //output:30

const:

• It cannot be redeclared and reassigned in the program.

• Once we declared the variable using const, then we cannot able to redclared and reassigned the value.

• const a = 30;
a = 20; //reassigned(error)
const a = 10; //redeclared(error)
console.log(a) //output:30