const getValue = (x) => {
  console.log(`Getting: ${x}`);
  return x;
};

const obj = { name: null };

const result = obj.name || getValue('default') && getValue('final');
console.log(`Result: ${result}`);

function createCounter() {
  let count = 0;
  
  const counter = {
    increment() {
      count++;
      return count;
    },
    getCount() {
      return count;
    }
  };
  
  return counter;
}

let c1 = createCounter();
c1.increment();
c1.increment();

let c2 = c1;
c1 = null;

console.log(c2.getCount());

const sym1 = Symbol('test');
const sym2 = Symbol('test');
const obj = {
  [sym1]: 'first',
  [sym2]: 'second',
  regular: 'third'
};

const keys = Object.keys(obj);
const symbols = Object.getOwnPropertySymbols(obj);
const allProps = Reflect.ownKeys(obj);

console.log(keys.length);
console.log(symbols.length);
console.log(allProps.length);
console.log(sym1 === sym2);

const sym1 = Symbol('test');
const sym2 = Symbol('test');
const obj = {
  [sym1]: 'first',
  [sym2]: 'second',
  regular: 'third'
};

const keys = Object.keys(obj);
const symbols = Object.getOwnPropertySymbols(obj);
const allProps = Reflect.ownKeys(obj);

console.log(keys.length);
console.log(symbols.length);
console.log(allProps.length);
console.log(sym1 === sym2);

async function fetchData() {
  return Promise.resolve('data');
}

async function processData() {
  console.log('start');
  const result = fetchData();
  console.log(typeof result);
  const data = await fetchData();
  console.log(typeof data);
  console.log('end');
}

processData();

const arr = [1, 2, 3, 4, 5];
const result = arr
  .map(x => x * 2)
  .filter(x => x > 5)
  .reduce((acc, val) => {
    return acc + (val % 3 === 0 ? val : 0);
  }, 0);

console.log(result);

const team = {
  members: ['Alice', 'Bob', 'Charlie'],
  [Symbol.iterator]: function*() {
    let index = 0;
    while(index < this.members.length) {
      yield this.members[index++].toUpperCase();
    }
  }
};

const result = [];
for (const member of team) {
  result.push(member);
}

console.log(result.join('-'));

function createCounter() {
  let count = 0;
  
  const counter = {
    increment() {
      count++;
      return count;
    },
    getCount() {
      return count;
    }
  };
  
  return counter;
}

let c1 = createCounter();
c1.increment();
c1.increment();

let c2 = c1;
c1 = null;

console.log(c2.getCount());

const obj = {};
let value = 0;

Object.defineProperty(obj, 'prop', {
  get() {
    return value;
  },
  set(newValue) {
    value = newValue + 1;
  },
  configurable: true,
  enumerable: true
});

obj.prop = 10;
console.log(obj.prop);

function* outer() {
  yield 1;
  yield* inner();
  yield 4;
}

function* inner() {
  yield 2;
  yield 3;
}

const gen = outer();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);

function* counter() {
  let i = 1;
  while (true) {
    const reset = yield i++;
    if (reset) {
      i = 1;
    }
  }
}

const gen = counter();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next(true).value);
console.log(gen.next().value);

const config = { api: 'v1', timeout: 5000 };
Object.seal(config);

const settings = { theme: 'dark', lang: 'en' };
Object.freeze(settings);

config.api = 'v2';
config.retries = 3;
settings.theme = 'light';
settings.debug = true;

console.log(config.api);
console.log(config.retries);
console.log(settings.theme);
console.log(settings.debug);

const map = new Map();
const key1 = {};
const key2 = key1;

map.set(key1, "Value for key1");
map.set(key2, "Value for key2");

console.log(map.get(key2));
console.log(map.get(key1));

async function foo() {
  console.log('Start');
  await Promise.resolve().then(() => {
    console.log('Inside Promise');
  });
  console.log('End');
}

foo();
console.log('Outside');

console.log('1');

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

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

queueMicrotask(() => console.log('4'));

setTimeout(() => console.log('5'), 0);

Promise.resolve().then(() => {
  console.log('6');
  return Promise.resolve();
}).then(() => console.log('7'));

console.log('8');

const pipe = (...fns) => (value) => fns.reduce((acc, fn) => fn(acc), value);

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

const transform = pipe(
  add(5),
  multiply(3),
  subtract(2)
);

console.log(transform(4));
console.log(transform(0));

class LightMachine {
  constructor() {
    this.states = {
      green: { next: 'yellow' },
      yellow: { next: 'red' },
      red: { next: 'green' }
    };
    this.currentState = 'green';
  }

  transition() {
    this.currentState = this.states[this.currentState].next;
    return this.currentState;
  }
}

const lightMachine = new LightMachine();
let result = '';
for (let i = 0; i < 5; i++) {
  result += lightMachine.transition() + ' ';
}
console.log(result.trim());