function checkTDZ() {
  console.log(typeof undeclaredVar);

  try {
    console.log(typeof letVar);
  } catch (e) {
    console.log(`Caught: ${e.constructor.name}`);
  }

  let letVar = "initialized";

  const result = (() => {
    let x = 10;
    return function () {
      let x = x + 5;
      return x;
    };
  })();

  try {
    console.log(result());
  } catch (e) {
    console.log(`Caught: ${e.constructor.name}`);
  }
}

checkTDZ();

const str = "  Hello, World!  ";

const result = str
  .trim()
  .split(", ")
  .map((word, i) => {
    return i === 0
      ? word.toUpperCase()
      : word.replace(/!$/, "").split("").reverse().join("") + "?";
  })
  .join(" | ");

const [first, ...rest] = result.split(" | ");
const final = `${first} | ${rest.join(" & ")}`;

console.log(final);

const p1 = new Promise((resolve) => {
  console.log("A");
  resolve("B");
});

const p2 = p1.then((val) => {
  console.log(val);
  return "C";
});

p2.then((val) => {
  console.log(val);
});

console.log("D");

const prefix = 'user';
const id = 42;
const role = 'admin';

const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1);

const profile = {
  [`${prefix}_${id}`]: 'Marcus',
  [Symbol.iterator]: null,
  [`get${capitalize(role)}`]: () => 'full-access',
  [`${prefix}Count`]: 3,
};

const dynamicKey = `${prefix}_${id}`;

console.log(
  profile[dynamicKey],
  profile[`get${capitalize(role)}`](),
  profile[`${prefix}Count`] * id,
  Object.keys(profile).length
);

const values = [0.1 + 0.2, NaN, Infinity, -0, 42.6789];

const results = values.map((v, i) => {
  if (i === 0) return Number.isInteger(v) + " " + v.toFixed(1);
  if (i === 1) return Number.isFinite(v) + " " + Number.isNaN(v);
  if (i === 2) return Number.isFinite(v) + " " + isFinite(v);
  if (i === 3) return Object.is(v, -0) + " " + (v === 0);
  if (i === 4) return v.toPrecision(4) + " " + Math.trunc(v);
});

results.forEach(r => console.log(r));

class Animal {
  #sound;

  constructor(name, sound) {
    this.name = name;
    this.#sound = sound;
  }

  speak() {
    return `${this.name} says ${this.#sound}`;
  }

  static create(name, sound) {
    return new this(name, sound);
  }
}

class Dog extends Animal {
  #tricks = [];

  constructor(name) {
    super(name, "woof");
  }

  learn(trick) {
    this.#tricks.push(trick);
    return this;
  }

  perform() {
    return `${this.name} performs: ${this.#tricks.join(", ")}`;
  }
}

const rex = Dog.create("Rex", "bark");
rex.learn("sit").learn("shake").learn("roll over");

console.log(rex.speak());
console.log(rex.perform());
console.log(rex instanceof Animal);
console.log(rex instanceof Dog);

const user = {
  profile: {
    name: "Marcus",
    score: 0,
    nickname: null,
    bio: undefined,
  },
};

user.profile.nickname ??= "Anonymous";
user.profile.bio ??= "No bio provided";
user.profile.score ??= 100;
user.profile.rank ??= "Beginner";

const { name, score, nickname, bio, rank } = user.profile;
console.log(`${name} | ${score} | ${nickname} | ${bio} | ${rank}`);