JavaScript Objects: Introduction, Overview, and Basics

// Creating an object literal for a book
let book = {
    title: "JavaScript: The Good Parts",
    author: "Douglas Crockford",
    publishedYear: 2008,
    pages: 176,
    topics: ["JavaScript", "Programming", "Web Development"]
};

// Creating an empty object first
let car = new Object();

// Adding properties one by one
car.make = "Toyota";
car.model = "Corolla";
car.year = 2022;
car.isElectric = false;
car.features = ["Bluetooth", "Backup Camera", "Navigation"];

// Accessing properties using dot notation
console.log(book.title);        // "JavaScript: The Good Parts"
console.log(car.make);          // "Toyota"
console.log(book.topics[0]);    // "JavaScript" (accessing array elements inside objects)

// Accessing properties using bracket notation
console.log(book["title"]);     // "JavaScript: The Good Parts"
console.log(car["make"]);       // "Toyota"

// When you need to use variables or have special characters
let propertyName = "title";
console.log(book[propertyName]); // "JavaScript: The Good Parts"

// Creating an object with special characters in property names
let person = {
    "first name": "John",
    "last name": "Doe"
};

// You must use bracket notation for properties with spaces
console.log(person["first name"]); // "John"
// This would cause an error: person.first name

// Modifying an existing property
book.publishedYear = 2009;  // Changed from 2008

// Adding a new property
book.isInPrint = true;

// Adding a method (function as a property)
book.getSummary = function() {
    return `${this.title} by ${this.author}, published in ${this.publishedYear}`;
};

// Calling the method
console.log(book.getSummary());  // "JavaScript: The Good Parts by Douglas Crockford, published in 2009"

// Deleting a property
delete book.pages;

// Now this will return undefined
console.log(book.pages);  // undefined

// Creating an object
let originalCar = {
    make: "Honda",
    model: "Civic",
    year: 2020
};

// Assigning to a new variable
let copiedCar = originalCar;

// Modifying the "copy" will also change the original
copiedCar.year = 2021;

// Both show the updated year
console.log(originalCar.year);  // 2021
console.log(copiedCar.year);    // 2021

// Creating a true copy using Object.assign()
let trueCopy1 = Object.assign({}, originalCar);

// Or using the spread operator (more modern)
let trueCopy2 = {...originalCar};

// Now modifying the copy won't affect the original
trueCopy1.year = 2022;
console.log(originalCar.year);  // Still 2021
console.log(trueCopy1.year);    // 2022

// Iterating through all properties
let person = {
    name: "Alice",
    age: 30,
    city: "New York",
    occupation: "Developer"
};

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

// Output:
// name: Alice
// age: 30
// city: New York
// occupation: Developer

// Get all keys as an array
let keys = Object.keys(person);
console.log(keys);  // ["name", "age", "city", "occupation"]

// Get all values as an array
let values = Object.values(person);
console.log(values);  // ["Alice", 30, "New York", "Developer"]

// Get key-value pairs as arrays
let entries = Object.entries(person);
console.log(entries);  
// [["name", "Alice"], ["age", 30], ["city", "New York"], ["occupation", "Developer"]]

// You can use these with array methods like forEach
Object.keys(person).forEach(key => {
    console.log(`${key}: ${person[key]}`);
});

// Creating a nested object structure
let student = {
    name: "Maria Garcia",
    age: 22,
    contact: {
        email: "maria@example.com",
        phone: "555-123-4567",
        address: {
            street: "123 University Ave",
            city: "Boston",
            state: "MA",
            zip: "02134"
        }
    },
    courses: [
        {
            id: "CS101",
            title: "Intro to Computer Science",
            grade: "A"
        },
        {
            id: "MATH201",
            title: "Calculus II",
            grade: "B+"
        }
    ]
};

// Accessing nested properties
console.log(student.contact.email);  // "maria@example.com"
console.log(student.contact.address.city);  // "Boston"
console.log(student.courses[0].title);  // "Intro to Computer Science"

// Define a shopping cart using an object
let shoppingCart = {
    // Properties
    items: [],
    totalPrice: 0,
    
    // Methods
    addItem: function(name, price, quantity = 1) {
        // Create a new item object
        let newItem = {
            id: Date.now(), // Using timestamp as a simple unique ID
            name: name,
            price: price,
            quantity: quantity,
            subtotal: price * quantity
        };
        
        // Add to items array
        this.items.push(newItem);
        
        // Update total price
        this.calculateTotal();
        
        console.log(`Added ${quantity} ${name}(s) to cart`);
        return newItem;
    },
    
    removeItem: function(itemId) {
        // Find the item index
        let index = this.items.findIndex(item => item.id === itemId);
        
        if (index !== -1) {
            let removedItem = this.items[index];
            this.items.splice(index, 1);
            this.calculateTotal();
            console.log(`Removed ${removedItem.name} from cart`);
        } else {
            console.log("Item not found in cart");
        }
    },
    
    updateQuantity: function(itemId, newQuantity) {
        // Find the item
        let item = this.items.find(item => item.id === itemId);
        
        if (item) {
            item.quantity = newQuantity;
            item.subtotal = item.price * newQuantity;
            this.calculateTotal();
            console.log(`Updated ${item.name} quantity to ${newQuantity}`);
        } else {
            console.log("Item not found in cart");
        }
    },
    
    calculateTotal: function() {
        this.totalPrice = this.items.reduce((sum, item) => sum + item.subtotal, 0);
    },
    
    displayCart: function() {
        console.log("Shopping Cart Contents:");
        console.log("=======================");
        
        if (this.items.length === 0) {
            console.log("Cart is empty");
        } else {
            this.items.forEach(item => {
                console.log(`${item.name} - $${item.price} x ${item.quantity} = $${item.subtotal}`);
            });
            console.log("=======================");
            console.log(`Total: $${this.totalPrice.toFixed(2)}`);
        }
    },
    
    clearCart: function() {
        this.items = [];
        this.totalPrice = 0;
        console.log("Cart cleared");
    }
};

// Using the shopping cart
let laptop = shoppingCart.addItem("Laptop", 999.99);
shoppingCart.addItem("Mouse", 24.99, 2);
shoppingCart.displayCart();

// Update quantity
shoppingCart.updateQuantity(laptop.id, 2);
shoppingCart.displayCart();

// Remove an item
shoppingCart.removeItem(laptop.id);
shoppingCart.displayCart();