Primitive Data Types

JavaScript data types define what kind of value a variable holds.

JavaScript has primitive and non-primitive data types.

Primitive Data Types in JavaScript

Primitive data types store single, simple values.

1. String

Used to store text data.

Example:

let name = "Ritik";
let message = 'Hello JavaScript';

• Strings can use single (‘ ‘) or double (” “) quotes

2. Number

Used to store numbers, including integers and decimals.

Example:

let age = 25;
let price = 99.99;

JavaScript does not have separate int or float types.

3. Boolean

Used to store true or false values.

Example:

let isLoggedIn = true;
let hasPermission = false;

Booleans are commonly used in conditions.

4. Undefined

A variable that is declared but not assigned any value is undefined.

Example:

let score;
console.log(score); // undefined

5. Null

null means no value or empty value, intentionally set by the programmer.

Example:

let data = null;

Difference:

• undefined → value not assigned
• null → value intentionally empty

6. BigInt

Used to store very large integers that exceed the safe limit of number.

Example:

let bigNumber = 12345678901234567890n;

• Ends with n
• Used in finance, cryptography, large calculations

7. Symbol

Used to create unique identifiers.

Example:

let id = Symbol("userId");

• Each Symbol is unique
• Used in advanced JavaScript scenarios

Checking Data Type Using typeof

You can check the type of a variable using typeof.

Example:

typeof "Hello";    // string
typeof 10;         // number
typeof true;       // boolean
typeof undefined;  // undefined
typeof null;       // object (JavaScript quirk)