JavaScript is a scripting language used to create interactive web pages. It runs in the browser and can also run on servers using Node.js.

Primitive:

Number

String

Boolean

Null

Undefined

BigInt

Symbol

Non-Primitive:

Object

Array

Function

var a = 10;

let b = 20;

const c = 30;

Hoisting moves variable and function declarations to the top before execution.

console.log(a);

var a = 10;

Output:

undefined

• Checks value only
•   Performs type conversion

5 == "5" // true

===

• Checks value and type

5 === "5" // false

Represents an intentional empty value.

let data = null;

Variable declared but not assigned.

let name;

console.log(name);

Output

undefined

Stores multiple values.

let colors = ["Red", "Blue", "Green"];

let fruits = ["Apple", "Orange"];

console.log(fruits[0]);

Output

Apple

Stores data as key-value pairs.

let person = {

    name: "Siva",

    age: 37

};