JavaScript Object Kya Hote Hai?

Introduction to Objects

JavaScript me object ek complex data type hai jo related data aur functionality ko ek collection me store karta hai. Yeh collection key-value pairs se bana hota hai. Har key (jise property bhi kehte hain) ek unique identifier hoti hai, aur uski value koi bhi data type ho sakti hai—jaise string, number, array, ya even doosra object.

Objects real-world cheezon (jaise ek car, ek person) ko represent karne ke liye perfect hain.

Object Kaise Banayein?

1. Object Literal (Recommended)

Yeh object banane ka sabse common aur simple tarika hai. Isme curly braces {} ka use hota hai.

let person = {
  name: "Rahul",
  age: 25,
  city: "Delhi"
};

2. Using new Object() Constructor

Yeh object banane ka ek aur tarika hai, halaanki yeh kam use hota hai.

var person = new Object();
person.name = "Amit";
person.age = 25;

Object Properties ko Access Karna

Object ki properties ko access karne ke do tarike hain:

1. Dot Notation (.)

Yeh sabse aasan tarika hai. Aap object ke naam ke baad dot laga kar property ka naam likhte hain.

console.log(person.name); // Output: Rahul

2. Bracket Notation ([])

Iska use tab hota hai jab property ka naam dynamic ho ya usme special characters (jaise space) hon.

console.log(person["age"]); // Output: 25

let key = "city";
console.log(person[key]); // Output: Delhi

Adding, Updating, and Deleting Properties

JavaScript objects dynamic hote hain, yaani aap unki properties ko kabhi bhi change kar sakte hain.

let student = { name: "Rahul", age: 20 };

// 1. Add a new property
student.class = "12th";
console.log(student); // { name: 'Rahul', age: 20, class: '12th' }

// 2. Update an existing property
student.age = 21;
console.log(student.age); // 21

// 3. Delete a property
delete student.name;
console.log(student); // { age: 21, class: '12th' }

Object Methods and 'this' Keyword

Jab ek object ki property ki value ek function hoti hai, toh use method kehte hain. Methods object ke data par actions perform karte hain. this keyword ka use karke ek method apne hi object ki doosri properties ko access kar sakta hai.

let person = {
  name: "Priya",
  greet: function() {
    console.log("Hello, my name is " + this.name);
  }
};

person.greet(); // Output: Hello, my name is Priya

Looping Through Object Properties (for...in)

for...in loop ka use karke aap ek object ki sabhi properties ko iterate kar sakte hain.

const student = { name: "Rahul", age: 20, course: "BCA" };

for (let key in student) {
  console.log(key + ": " + student[key]);
}
// Output:
// name: Rahul
// age: 20
// course: BCA

Key Takeaways

• JavaScript me object, key-value pairs ka ek collection hai.
• Properties ko access karne ke liye dot notation (obj.key) ya bracket notation (obj['key']) ka use hota hai.
• Jab ek property ki value ek function hoti hai, toh use method kehte hain.
• this keyword ka use method ke andar uske apne object ko refer karne ke liye hota hai.
• for...in loop ka use karke object ki properties par iterate kiya ja sakta hai.