JavaScript Me Data Types Kya Hote Hain?

Introduction to Data Types

JavaScript ek "dynamically typed" language hai, jiska matlab hai ki aapko variable declare karte waqt uska data type batane ki zaroorat nahi hoti. Variable kisi bhi type ka data store kar sakta hai. JavaScript ke data types ko do mukhya categories me divide kiya gaya hai:

• Primitive Types: Simple data values.
• Reference Types (Non-Primitive): Complex data structures.

1. Primitive Data Types

Primitive data types immutable hote hain (unhe change nahi kiya ja sakta) aur unki value directly variable me store hoti hai. Jab aap ek primitive value ko doosre variable me copy karte hain, toh ek nayi, independent copy banti hai.

(A) Number

Yeh integers aur floating-point numbers dono ko represent karta hai.

let age = 25;
let price = 99.99;

(B) String

Characters ka sequence, jo text ko represent karta hai. Ise single (' '), double (" "), ya backticks (``) me likha jaata hai.

let name = "Rahul";
let greeting = 'Hello, World!';

(C) Boolean

Sirf do values represent karta hai: true ya false. Iska use logical operations me hota hai.

let isStudent = true;
let hasLicense = false;

(D) Undefined

Jab ek variable declare kiya jaata hai par use koi value assign nahi ki jaati, toh uski value undefined hoti hai.

let notAssigned;
console.log(notAssigned); // Output: undefined

(E) Null

Yeh 'intentional absence of any object value' ko represent karta hai. Yeh ek assigned value hai, jo 'empty' ya 'nothing' ko darshata hai.

let emptyValue = null;

(F) Symbol (ES6)

Yeh ek unique aur immutable value create karta hai, jiska use object properties ke liye unique identifiers ke roop me hota hai.

const sym1 = Symbol('id');
const sym2 = Symbol('id');
console.log(sym1 === sym2); // Output: false

(G) BigInt (ES11)

Yeh bohot bade integers ko represent karne ke liye use hota hai, jo Number type ki limit se bahar hain. Iske end me `n` lagaya jaata hai.

const bigNumber = 9007199254740991n;
console.log(bigNumber + 1n); // Output: 9007199254740992n

2. Reference Data Types (Non-Primitive)

Reference types actual value ko store nahi karte, balki memory me us value ka reference (address) store karte hain. Jab aap ek reference type ko copy karte hain, toh sirf reference copy hota hai, actual object nahi.

(A) Object

Yeh key-value pairs ka collection hota hai, jisme related data aur functionality ko group kiya jaata hai.

let person = {
  name: "Amit",
  age: 30
};
console.log(person.name); // Output: Amit

(B) Array

Yeh ek ordered list hai jo multiple values ko ek single variable me store kar sakti hai.

let fruits = ["Apple", "Mango", "Banana"];
console.log(fruits[0]); // Output: Apple

(C) Function

JavaScript me, functions bhi objects hote hain. Yeh ek reusable code block hai jo specific task perform karta hai.

function greet(name) {
  return `Hello, ${name}!`;
}
console.log(greet("Priya")); // Output: Hello, Priya!

Primitive vs. Reference Types

Key Takeaways

• JavaScript me Primitive (Number, String, etc.) aur Reference (Object, Array) do tarah ke data types hote hain.
• Primitive types immutable hote hain aur unki value copy hoti hai.
• Reference types mutable hote hain aur unka reference copy hota hai.
• typeof operator ka use karke aap kisi bhi variable ka data type check kar sakte hain.