Introduction to Objects

Objects are collections of key-value pairs. They are the most important data structure in JavaScript — almost everything in JS is an object.

Creating Objects

let person = {
    name: "Alice",
    age: 25,
    city: "London",
    isStudent: true
};

Accessing Properties

// Dot notation (preferred)
console.log(person.name);   // "Alice"
console.log(person.age);    // 25

// Bracket notation (for dynamic keys)
console.log(person["city"]);  // "London"

let key = "name";
console.log(person[key]);    // "Alice"

Modifying Objects

// Change a property
person.age = 26;

// Add a new property
person.email = "alice@example.com";

// Delete a property
delete person.isStudent;

Objects with Methods

let calculator = {
    add: function(a, b) {
        return a + b;
    },
    // Shorthand method syntax
    subtract(a, b) {
        return a - b;
    }
};

console.log(calculator.add(3, 5));      // 8
console.log(calculator.subtract(10, 4)); // 6

Nested Objects

let user = {
    name: "Alice",
    address: {
        street: "123 Main St",
        city: "London",
        country: "UK"
    }
};

console.log(user.address.city);  // "London"

Checking Properties

"name" in person;                 // true
person.hasOwnProperty("email");   // true
Object.keys(person);              // ["name", "age", "city", "email"]
Object.values(person);            // ["Alice", 26, "London", "alice@..."]