// ES5 Example
var numbers = [1, 2, 3, 4, 5];
var doubled = [];

for (var i = 0; i < numbers.length; i++) {
  doubled.push(numbers[i] * 2);
}

function greet(name) {
  return "Hello, " + name + "!";
}

var formatNumber = function(num) {
  return num.toFixed(2);
};

var user = {
  name: "John",
  age: 30,
  sayHello: function() {
    var self = this;
    setTimeout(function() {
      console.log(self.name + " says hello!");
    }, 1000);
  }
};

// Constructor function
function Person(name, age) {
  this.name = name;
  this.age = age;
}

Person.prototype.greet = function() {
  return "Hi, I'm " + this.name;
};

// Create a new instance
var john = new Person("John", 30);

// ES6 Example
const numbers = [1, 2, 3, 4, 5];
const doubled = numbers.map(num => num * 2);

const greet = name => `Hello, ${name}!`;

const formatNumber = num => num.toFixed(2);

const user = {
  name: "John",
  age: 30,
  sayHello() {
    setTimeout(() => {
      console.log(`${this.name} says hello!`);
    }, 1000);
  }
};

// Destructuring
const { name, age } = user;

// Spread operator
const newArray = [...numbers, 6, 7, 8];

// Default parameters
function multiply(a, b = 1) {
  return a * b;
}

// Classes
class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
  
  greet() {
    return `Hi, I'm ${this.name}`;
  }
}

// Create a new instance
const john = new Person("John", 30);

// Async/await example
async function fetchData() {
  try {
    const response = await fetch('https://api.example.com/data');
    const data = await response.json();
    return data;
  } catch (error) {
    console.error('Error:', error);
  }
}