function* generateSequence() {
  let i = 1;
  while (i <= 3) {
    yield i++;
  }
}

function* extendSequence() {
  yield* generateSequence();
  yield* [4, 5];
  yield 6;
}

const generator = extendSequence();
const result = [];

for (const value of generator) {
  if (value % 2 === 0) {
    result.push(value * 2);
  } else {
    result.push(value);
  }
}

console.log(result);

const privateData = new WeakMap();

function Person(name) {
  privateData.set(this, { name, secretCount: 0 });
  
  this.greet = function() {
    const data = privateData.get(this);
    data.secretCount++;
    return `Hello, my name is ${data.name}`;
  };
  
  this.getSecretCount = function() {
    return privateData.get(this).secretCount;
  };
}

const alice = new Person('Alice');
alice.greet();
alice.greet();

const result = [
  privateData.has(alice),
  alice.name,
  alice.getSecretCount()
];

console.log(result);

const user = {
  name: 'Alice',
  age: 30
};

const handler = {
  get(target, prop) {
    if (prop in target) {
      return target[prop];
    }
    return `Property '${prop}' doesn't exist`;
  },
  set(target, prop, value) {
    if (prop === 'age' && typeof value !== 'number') {
      console.log('Age must be a number');
      return false;
    }
    target[prop] = value;
    return true;
  }
};

const proxy = new Proxy(user, handler);
proxy.age = '32';
proxy.age = 32;
console.log(proxy.job);

function executePromises() {
  console.log(1);
  
  setTimeout(() => {
    console.log(2);
  }, 0);
  
  Promise.resolve().then(() => {
    console.log(3);
    setTimeout(() => {
      console.log(4);
    }, 0);
  }).then(() => {
    console.log(5);
  });
  
  console.log(6);
}

executePromises();

function main() {
  console.log(1);
  
  setTimeout(() => console.log(2), 0);
  
  Promise.resolve().then(() => {
    console.log(3);
    setTimeout(() => console.log(4), 0);
  }).then(() => console.log(5));
  
  Promise.resolve().then(() => console.log(6));
  
  console.log(7);
}

main();

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('-'));