async function getData() {
  return Promise.resolve(1);
}

async function process() {
  try {
    const x = await getData();
    const y = await Promise.resolve(x + 1);
    console.log(y + await Promise.resolve(1));
  } catch(err) {
    console.log('Error');
  }
}

process();

const cache = new WeakMap();
const obj1 = { id: 1 };
const obj2 = { id: 2 };

cache.set(obj1, 'data1');
cache.set(obj2, 'data2');

obj2.newProp = 'test';

console.log(cache.has(obj1), cache.has(obj2), cache.has({ id: 1 }));

const counter = {
  count: 0,
  increment() {
    this.count++;
    return this.count;
  }
};

const inc = counter.increment;
const boundInc = counter.increment.bind(counter);

console.log([
  counter.increment(),
  inc(),
  boundInc(),
  counter.count
]);

let x = 1;
function outer() {
  let x = 2;
  function inner() {
    console.log(x);
    let x = 3;
  }
  inner();
}
outer();

function createCounter() {
  let count = 0;
  
  return function() {
    count++;
    return count;
  };
}

const counter1 = createCounter();
const counter2 = createCounter();

counter1();
counter1();
counter2();

const result = counter1() + counter2();
console.log(result);

function* fibonacci() {
  let [prev, curr] = [0, 1];
  while (true) {
    yield curr;
    [prev, curr] = [curr, prev + curr];
  }
}

function* take(iterable, limit) {
  for (const item of iterable) {
    if (limit <= 0) return;
    yield item;
    limit--;
  }
}

const fibs = [...take(fibonacci(), 5)];
fibs.push(fibs[0] + fibs[1]);
console.log(fibs);

function* counter() {
  let count = 1;
  while (true) {
    const reset = yield count++;
    if (reset) {
      count = 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 user = {
  profile: {
    name: 'Alice',
    social: null,
    getDetails() {
      return { verified: true };
    }
  }
};

const result = [
  user?.profile?.name,
  user?.profile?.social?.handle,
  user.profile.getDetails?.()?.verified,
  user?.nonExistent?.property
];

console.log(result);