JavaScript

In JavaScript, an object is a complex data type used to store key-value pairs. These key-value pairs are also known as properties and can hold any value—like strings, numbers, arrays, or even functions (called methods when inside objects).

Objects help organize related data and functionalities in a structured way.

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🗂️ Object Syntax

const person = {
  name: "John",
  age: 30,
  isEmployed: true,
  greet: function () {
    console.log("Hello!");
  }
};

• name, age, and isEmployed are properties
• greet is a method (a function inside an object)

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🧾 Accessing Object Properties

🔹 Dot Notation

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

🔹 Bracket Notation

console.log(person["age"]); // Output: 30

Bracket notation is useful when property names are stored in a variable or contain spaces.

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🛠️ Modifying Object Properties

person.age = 31;
person["name"] = "Jane";

You can add new properties too:

person.city = "New York";

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🗑️ Deleting Properties

delete person.isEmployed;

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✅ Checking if a Property Exists

console.log("age" in person); // true
console.log(person.hasOwnProperty("city")); // true

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📦 Creating Objects Dynamically

Using Object Constructor

const car = new Object();
car.brand = "Toyota";
car.year = 2022;

Using Factory Function

function createUser(name, email) {
  return {
    name,
    email,
    isLoggedIn: false
  };
}

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🧬 Nested Objects

const user = {
  name: "Alice",
  address: {
    street: "123 Main St",
    city: "Mumbai"
  }
};

console.log(user.address.city); // Mumbai

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🔄 Looping Through an Object

for (let key in person) {
  console.log(key + ": " + person[key]);
}

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🧠 Why Use Objects?

• To group related data and behavior (methods)
• To build complex data structures (e.g., user profiles, settings)
• They’re the foundation of many concepts in JavaScript like classes, APIs, and JSON

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