Αντιστοίχιση Προτύπων στη JavaScript: Guards και Εξαγωγή - Ένας Ολοκληρωμένος Οδηγός

            const person = {
  name: 'Alice',
  age: 30,
  address: {
    city: 'New York',
    country: 'USA'
  }
};

const { name, age } = person; // Extract name and age
console.log(name); // Output: Alice
console.log(age); // Output: 30

const { address: { city, country } } = person; // Extract city and country from nested address
console.log(city); // Output: New York
console.log(country); // Output: USA

            

              
                Copy
              
            
          

            const numbers = [1, 2, 3, 4, 5];

const [first, second, , fourth] = numbers; // Extract first, second, and fourth elements
console.log(first); // Output: 1
console.log(second); // Output: 2
console.log(fourth); // Output: 4

const [head, ...tail] = numbers; // Extract head and tail of the array
console.log(head); // Output: 1
console.log(tail); // Output: [2, 3, 4, 5]

            

              
                Copy
              
            
          

            function processProduct(product) {
  if (product.type === 'book' && product.price > 20) {
    console.log(`Processing expensive book: ${product.title}`);
  } else if (product.type === 'book') {
    console.log(`Processing book: ${product.title}`);
  } else if (product.type === 'electronic' && product.warrantyMonths > 12) {
    console.log(`Processing electronic with extended warranty: ${product.name}`);
  } else if (product.type === 'electronic') {
    console.log(`Processing electronic: ${product.name}`);
  } else {
    console.log(`Unknown product type: ${product.type}`);
  }
}

const book1 = { type: 'book', title: 'The Lord of the Rings', price: 25 };
const book2 = { type: 'book', title: 'The Hobbit', price: 15 };
const electronic1 = { type: 'electronic', name: 'Laptop', warrantyMonths: 18 };
const electronic2 = { type: 'electronic', name: 'Smartphone', warrantyMonths: 6 };

processProduct(book1); // Output: Processing expensive book: The Lord of the Rings
processProduct(book2); // Output: Processing book: The Hobbit
processProduct(electronic1); // Output: Processing electronic with extended warranty: Laptop
processProduct(electronic2); // Output: Processing electronic: Smartphone

            

              
                Copy
              
            
          

            function convertCurrency(amount, currency) {
  if (currency === 'USD' && amount > 100) {
    return amount * 0.85; // Conversion to EUR for USD > 100
  } else if (currency === 'USD') {
    return amount * 0.9; // Conversion to EUR for USD <= 100
  } else if (currency === 'EUR') {
    return amount * 1.1; // Conversion to USD
  } else if (currency === 'JPY') {
    return amount * 0.0075; // Conversion to USD
  } else {
    return null; // Unknown currency
  }
}

console.log(convertCurrency(150, 'USD')); // Output: 127.5
console.log(convertCurrency(50, 'USD'));  // Output: 45
console.log(convertCurrency(100, 'EUR')); // Output: 110
console.log(convertCurrency(10000, 'JPY')); // Output: 75
console.log(convertCurrency(100, 'GBP'));  // Output: null

            

              
                Copy
              
            
          

            function validateInput(input) {
  if (typeof input === 'string' && input.length > 0 && input.length < 50) {
    console.log("Valid string input: " + input);
  } else if (typeof input === 'number' && input > 0 && input < 1000) {
    console.log("Valid number input: " + input);
  } else {
    console.log("Invalid input");
  }
}

validateInput("Hello"); //Valid string input: Hello
validateInput(123); //Valid number input: 123
validateInput(""); //Invalid input
validateInput(12345); //Invalid input

            

              
                Copy
              
            
          

            function processOrder(order) {
  const { customer: { name }, orderId, totalAmount } = order;
  console.log(`Processing order ${orderId} for customer ${name} with total amount ${totalAmount}`);
}

const order = {
  orderId: '12345',
  customer: {
    name: 'Bob',
    email: 'bob@example.com'
  },
  items: [
    { productId: 'A1', quantity: 2, price: 10 },
    { productId: 'B2', quantity: 1, price: 25 }
  ],
  totalAmount: 45
};

processOrder(order); // Output: Processing order 12345 for customer Bob with total amount 45

            

              
                Copy
              
            
          

            function handleApiResponse(response) {
  const { status, data: { user: { id, username, email } } } = response;
  if (status === 200) {
    console.log(`User ID: ${id}, Username: ${username}, Email: ${email}`);
  } else {
    console.log(`Error: ${response.message}`);
  }
}

const successResponse = {
  status: 200,
  data: {
    user: {
      id: 123,
      username: 'john.doe',
      email: 'john.doe@example.com'
    }
  }
};

const errorResponse = {
  status: 400,
  message: 'Invalid request'
};

handleApiResponse(successResponse); // Output: User ID: 123, Username: john.doe, Email: john.doe@example.com
handleApiResponse(errorResponse); // Output: Error: Invalid request

            

              
                Copy
              
            
          

            function processCoordinates(coordinates) {
  const { latitude: lat, longitude: lon } = coordinates;
  console.log(`Latitude: ${lat}, Longitude: ${lon}`);
}

const location = {
  latitude: 34.0522,
  longitude: -118.2437
};

processCoordinates(location); //Output: Latitude: 34.0522, Longitude: -118.2437

            

              
                Copy
              
            
          

            function processUserProfile(profile) {
  const { role, age, details: { name, email, country } } = profile;

  if (role === 'admin' && age > 18 && country === 'USA') {
    console.log(`Processing admin user ${name} from ${country} with email ${email}`);
  } else if (role === 'editor' && age > 21) {
    console.log(`Processing editor user ${name} with email ${email}`);
  } else {
    console.log(`Invalid user profile`);
  }
}

const adminProfile = {
  role: 'admin',
  age: 35,
  details: {
    name: 'John Doe',
    email: 'john.doe@example.com',
    country: 'USA'
  }
};

const editorProfile = {
  role: 'editor',
  age: 25,
  details: {
    name: 'Jane Smith',
    email: 'jane.smith@example.com',
    country: 'Canada'
  }
};

const invalidProfile = {
  role: 'user',
  age: 16,
  details: {
    name: 'Peter Jones',
    email: 'peter.jones@example.com',
    country: 'UK'
  }
};

processUserProfile(adminProfile); // Output: Processing admin user John Doe from USA with email john.doe@example.com
processUserProfile(editorProfile); // Output: Processing editor user Jane Smith with email jane.smith@example.com
processUserProfile(invalidProfile); // Output: Invalid user profile

            

              
                Copy
              
            
          

            function processTransaction(transaction) {
  const { method, amount, details: { cardNumber, expiryDate } } = transaction;

  if (method === 'credit_card' && amount > 100) {
    const fee = amount * 0.02; // 2% fee for credit card transactions over $100
    console.log(`Processing credit card transaction: Amount = ${amount}, Fee = ${fee}, Card Number = ${cardNumber}`);
  } else if (method === 'paypal') {
    const fee = 0.5; // Flat fee of $0.5 for PayPal transactions
    console.log(`Processing PayPal transaction: Amount = ${amount}, Fee = ${fee}`);
  } else {
    console.log(`Invalid transaction method`);
  }
}

const creditCardTransaction = {
  method: 'credit_card',
  amount: 150,
  details: {
    cardNumber: '1234-5678-9012-3456',
    expiryDate: '12/24'
  }
};

const paypalTransaction = {
  method: 'paypal',
  amount: 50,
  details: {}
};

const invalidTransaction = {
  method: 'wire_transfer',
  amount: 200,
  details: {}
};

processTransaction(creditCardTransaction); // Output: Processing credit card transaction: Amount = 150, Fee = 3, Card Number = 1234-5678-9012-3456
processTransaction(paypalTransaction); // Output: Processing PayPal transaction: Amount = 50, Fee = 0.5
processTransaction(invalidTransaction); // Output: Invalid transaction method

            

              
                Copy
              
            
          

            function processShape(shape) {
  switch (shape.type) {
    case 'circle':
      const { radius } = shape;
      console.log(`Processing circle with radius ${radius}`);
      break;
    case 'square':
      const { side } = shape;
      console.log(`Processing square with side ${side}`);
      break;
    case 'rectangle':
      const { width, height } = shape;
      console.log(`Processing rectangle with width ${width} and height ${height}`);
      break;
    default:
      console.log(`Unknown shape type: ${shape.type}`);
  }
}

const circle = { type: 'circle', radius: 5 };
const square = { type: 'square', side: 10 };
const rectangle = { type: 'rectangle', width: 8, height: 6 };

processShape(circle); // Output: Processing circle with radius 5
processShape(square); // Output: Processing square with side 10
processShape(rectangle); // Output: Processing rectangle with width 8 and height 6

            

              
                Copy
              
            
          

            function extractUserDetails(user) {
  if (user && user.name && user.email) {
    return { name: user.name, email: user.email };
  } else {
    return null;
  }
}

function processUser(user) {
  const details = extractUserDetails(user);
  if (details) {
    const { name, email } = details;
    console.log(`Processing user ${name} with email ${email}`);
  } else {
    console.log(`Invalid user data`);
  }
}

const validUser = { name: 'David Lee', email: 'david.lee@example.com' };
const invalidUser = { name: 'Sarah' };

processUser(validUser); // Output: Processing user David Lee with email david.lee@example.com
processUser(invalidUser); // Output: Invalid user data

            

              
                Copy