console.log('1');
setTimeout(() => console.log('2'), 0);
Promise.resolve().then(() => console.log('3'));
setTimeout(() => console.log('4'), 0);
console.log('5');
Promise.resolve().then(() => {
  console.log('6');
  return Promise.resolve();
}).then(() => console.log('7'));
queueMicrotask(() => console.log('8'));
console.log('9');

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);

function Vehicle(type) {
  this.type = type;
}

Vehicle.prototype.describe = function() {
  return `This is a ${this.type}`;
};

function Car(brand) {
  Vehicle.call(this, 'car');
  this.brand = brand;
}

Car.prototype = Object.create(Vehicle.prototype);
Car.prototype.constructor = Car;

Car.prototype.describe = function() {
  return Vehicle.prototype.describe.call(this) + ` made by ${this.brand}`;
};

const tesla = new Car('Tesla');
console.log(tesla.describe());
console.log(tesla.constructor.name);

const cache = new Map();

function createHandler(id) {
  const data = { id, value: new Array(1000).fill(id) };
  cache.set(id, data);
  
  return function(action) {
    if (action === 'get') return data;
    if (action === 'clear') cache.delete(id);
  };
}

const handler1 = createHandler('user-1');
const handler2 = createHandler('user-2');

handler1('clear');
console.log(cache.size);
console.log(handler1('get').id);

const nums = [1, 2, 3];
const obj = { a: 1, b: 2 };
const newObj = { ...obj, b: 3, ...obj };

const arr1 = [4, 5];
const arr2 = [6, 7];
const combined = [...nums, ...arr1, ...arr2];

const [first, ...rest] = combined;
const { a, ...remaining } = newObj;

console.log(newObj.b);
console.log(rest.length);
console.log(remaining.b);

const string = "“abc123def456ghi789";

const matches =
string.match(/\d+/g);
console. log(matches );

const firstArrayData = [ 'JavaScript', 'Universe' ];
const secondArrayData = [ 'JavaScript', 'Universe' ];

console.log(firstArrayData == secondArrayData);
console.log(firstArrayData === secondArrayData);

function createCounter() {
  let count = 0;
  return {
    increment: () => ++count,
    decrement: () => --count,
    getValue: () => count
  };
}

const counter1 = createCounter();
const counter2 = createCounter();
counter1.increment();
counter1.increment();
counter2.increment();
console.log(counter1.getValue() + counter2.getValue());

function createCounter() {
  let count = 0;
  return {
    increment: () => ++count,
    decrement: () => --count,
    get: () => count
  };
}

const counter1 = createCounter();
const counter2 = createCounter();
counter1.increment();
counter1.increment();
counter2.increment();
console.log(counter1.get(), counter2.get());
const { increment, get } = counter1;
increment();
console.log(get());

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);

const step1 = multiply(2);
const step2 = step1(3);
const result1 = step2(4);

const result2 = multiply(2)(3)(4);

const partialMultiply = multiply(5);
const result3 = partialMultiply(2)(3);

const doubler = multiply(2)(1);
const result4 = doubler(7);

console.log(result1, result2, result3, result4);

console.log('1');

setTimeout(() => console.log('2'), 0);

Promise.resolve().then(() => console.log('3'));

setTimeout(() => console.log('4'), 0);

Promise.resolve().then(() => {
  console.log('5');
  return Promise.resolve();
}).then(() => console.log('6'));

console.log('7');

let symbol1 = Symbol('denoscription');
let symbol2 = Symbol('denoscription');

const obj = {
  [symbol1]: 'value1',
  [symbol2]: 'value2'
};

console.log(obj[symbol1]);
console.log(symbol1 === symbol2);