const obj = { a: 1, b: 2 };
const proxy = new Proxy(obj, {
  get(target, prop) {
    return prop in target ? target[prop] : 0;
  }
});

console.log(proxy.a, proxy.b, proxy.c);

const target = { name: 'Sarah', age: 25 };

const handler = {
  get(obj, prop) {
    if (prop in obj) {
      return obj[prop];
    }
    return `Property '${prop}' not found`;
  },
  set(obj, prop, value) {
    obj[prop] = value.toString().toUpperCase();
    return true;
  }
};

const proxy = new Proxy(target, handler);
proxy.city = 'boston';
console.log(proxy.name);
console.log(proxy.city);
console.log(proxy.country);

class Rectangle {
  constructor(width, height) {
    this.width = width;
    this.height = height;
  }

  get area() {
    return this.width * this.height;
  }
}

const rectangle = new Rectangle(5, 10);
console.log(rectangle.area());

var a=[1,2,3,4,5];
a.every(x=>{
  console.log(x); 
  return x<4;
})

const numbers = [1, 2, 3];
numbers.push(4);
console.log(numbers);

class Counter {
  constructor(max) {
    this.max = max;
  }
  
  *[Symbol.iterator]() {
    let current = 0;
    while (current < this.max) {
      yield current++;
    }
  }
}

const counter = new Counter(3);
const result = [...counter, ...counter];
console.log(result);

const x = [1, 2, 3, 4, 5];
console.log(x.slice(1, 3));

const person = {
  name: "John",
  greet: function() {
    const getMessage = () => `Hello, ${this.name}`;
    return getMessage();
  }
};

console.log(person.greet());

const weakMap = new WeakMap();
const array = [{}, {}];

array.forEach(obj => weakMap.set(obj, obj));
const result = array.map(obj => weakMap.get(obj) === obj);

console.log(result);

const arr = Array.from({ length: 3 }, (_, i) => i * 2);

for (const i of arr) {
   console.log(i);
} 

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

const result = numbers
  .map(n => n * 2)
  .filter(n => n > 5)
  .reduce((acc, n, index) => {
    acc.sum += n;
    acc.indices.push(index);
    return acc;
  }, { sum: 0, indices: [] });

console.log(result.sum);
console.log(result.indices);

const array = Array.from({ length: 5 }, () => Math.random() > 0.5);

console.log(array);

const array = [1, 2, 3, 4, 5];
const [first, ...rest] = array;

const modified = rest.map((n, i) => i % 2 === 0 ? n * 2 : n);

console.log(first, modified);

function processData(data) {
  try {
    if (!data) {
      throw new TypeError('Data is missing');
    }
    
    const result = data.process();
    return result;
  } catch (error) {
    console.log(error instanceof ReferenceError ? 1 :
               error instanceof TypeError ? 2 :
               error instanceof SyntaxError ? 3 : 4);
  }
}

processData(null);

const add = x => y => x + y;
const multiply = x => y => x * y;
const subtract = x => y => x - y;

const result = add(10)(multiply(2)(subtract(5)(3)));
console.log(result);

setTimeout(() => {
  console.log('setTimeout 1');
  Promise.resolve().then(() => console.log('Promise 1'));
}, 0);

Promise.resolve().then(() => {
  console.log('Promise 2');
  setTimeout(() => console.log('setTimeout 2'), 0);
});

console.log('Sync');

const person = {
  name: "John",
  greet: function() {
    const getMessage = () => `Hello, ${this.name}`;
    return getMessage();
  }
};

console.log(person.greet());