Q281- What are the different data types in JavaScript?

JavaScript has two categories of data types: Primitive and Non-Primitive (Reference).

---

✅ 1. Primitive Data Types

Primitive types store single, immutable values.

🔹 Number

let a = 10;
let b = 3.14;

🔹 String

let name = "Teekam";

🔹 Boolean

let isLoggedIn = true;

🔹 Undefined

let x;

Declared but not assigned.

🔹 Null

let data = null;

Represents intentional absence of value.

🔹 Symbol (ES6)

const id = Symbol("id");

Used for unique identifiers.

🔹 BigInt

let big = 12345678901234567890n;

Used for very large integers.

---

✅ 2. Non-Primitive (Reference) Data Types

These store references, not actual values.

🔹 Object

const user = { name: "Teekam", age: 26 };

🔹 Array

const nums = [1, 2, 3];

🔹 Function

function greet() {}

🔹 Date

const today = new Date();

---

🔥 Key Differences

Feature	Primitive	Reference
Stored as	Value	Reference
Mutable	❌ No	✔ Yes
Compared by	Value	Reference
Example	number, string	object, array

---

🎯 Short Interview Answer

JavaScript has 7 primitive types: Number, String, Boolean, Undefined, Null, Symbol, and BigInt.
And non-primitive types like Object, Array, and Function, which are stored by reference.

---

⭐ Tip

Use typeof to check most types:

typeof 10;        // "number"
typeof "hi";      // "string"
typeof null;      // "object" ❗ (JS bug)