const num1 = 9007199254740992n;
const num2 = 1n;

const result1 = num1 + num2;
const result2 = Number(num1) + Number(num2);
const result3 = num1 + BigInt(1);
const result4 = String(num1) + String(num2);

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

function createSymbolDemo() {
  const obj = {};
  
  const sym1 = Symbol('description');
  const sym2 = Symbol('description');
  const sym3 = Symbol.for('shared');
  const sym4 = Symbol.for('shared');
  
  obj[sym1] = 'Value 1';
  obj[sym2] = 'Value 2';
  obj[sym3] = 'Value 3';
  obj[sym4] = 'Value 4';
  
  console.log(Object.keys(obj).length, sym1 === sym2, sym3 === sym4, obj[sym3]);
}

createSymbolDemo();

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();