function* counter(start, end) {
  for (let i = start; i <= end; i++) {
    yield i;
  }
}

function* pipeline() {
  const first = yield* counter(1, 3);
  console.log("Counter done:", first);

  yield "bridge";

  const second = yield* counter(7, 9);
  console.log("Counter done:", second);
}

const gen = pipeline();

const results = [];
let next = gen.next();
while (!next.done) {
  results.push(next.value);
  next = gen.next();
}

console.log(results);

const config = {
  host: "localhost",
  port: 3000,
  db: {
    name: "mydb",
    maxConnections: 10
  }
};

Object.freeze(config);

config.port = 9999;
config.db.maxConnections = 99;
config.newProp = "surprise";
delete config.host;

const sealed = Object.seal({ x: 1, y: 2 });
sealed.x = 100;
sealed.z = 999;
delete sealed.y;

console.log(config.port, config.db.maxConnections, config.host);
console.log(sealed.x, sealed.y, sealed.z);

async function fetchData(id) {
  if (id < 0) throw new Error("Invalid ID");
  return { id, value: id * 10 };
}

async function process() {
  const results = await Promise.allSettled([
    fetchData(1),
    fetchData(-1),
    fetchData(3),
  ]);

  results.forEach(({ status, value, reason }) => {
    if (status === "fulfilled") {
      console.log(`fulfilled: ${value.id} -> ${value.value}`);
    } else {
      console.log(`rejected: ${reason.message}`);
    }
  });
}

process();

const EventEmitter = (() => {
  const listeners = new WeakMap();

  return class {
    constructor() {
      listeners.set(this, {});
    }

    on(event, fn) {
      const map = listeners.get(this);
      (map[event] ??= []).push(fn);
      return this;
    }

    emit(event, ...args) {
      const map = listeners.get(this);
      (map[event] ?? []).forEach(fn => fn(...args));
      return this;
    }
  };
})();

const bus = new EventEmitter();
const log = [];

bus
  .on("data", val => log.push(`A:${val}`))
  .on("data", val => log.push(`B:${val}`))
  .on("done", ()  => log.push("done"));

bus.emit("data", 1).emit("data", 2).emit("done");

console.log(log.join(" | "));

class Vehicle {
  #speed = 0;

  constructor(brand) {
    this.brand = brand;
  }

  accelerate(amount) {
    this.#speed += amount;
    return this;
  }

  getSpeed() {
    return this.#speed;
  }

  toString() {
    return `${this.brand} @ ${this.#speed}km/h`;
  }
}

class Car extends Vehicle {
  #gear = 1;

  constructor(brand, model) {
    super(brand);
    this.model = model;
  }

  shiftUp() {
    this.#gear++;
    return this;
  }

  toString() {
    return `${super.toString()} [Gear ${this.#gear}]`;
  }
}

const car = new Car("Toyota", "Supra");
car.accelerate(60).accelerate(40).shiftUp().shiftUp();

console.log(car.toString());
console.log(car instanceof Car);
console.log(car instanceof Vehicle);
console.log(Object.getPrototypeOf(Car) === Vehicle);

const delay = (ms, val) => new Promise(res => setTimeout(res, ms, val));

async function pipeline(...fns) {
  return async (input) => {
    let result = input;
    for (const fn of fns) {
      result = await fn(result);
    }
    return result;
  };
}

const double  = async (x) => delay(10, x * 2);
const addTen  = async (x) => delay(10, x + 10);
const square  = async (x) => delay(10, x ** 2);

(async () => {
  const process = await pipeline(double, addTen, square);
  const output  = await process(3);
  console.log(output);
})();

const inventory = new Map([
  ["sword", { quantity: 3, weight: 15 }],
  ["shield", { quantity: 1, weight: 25 }],
  ["potion", { quantity: 10, weight: 2 }],
]);

inventory.set("bow", { quantity: 2, weight: 8 });
inventory.delete("shield");

const totalWeight = [...inventory.entries()].reduce((acc, [item, { quantity, weight }]) => {
  return acc + quantity * weight;
}, 0);

const heaviestItem = [...inventory.entries()].reduce((max, [item, data]) =>
  data.weight > max.weight ? { name: item, ...data } : max,
  { name: "", weight: 0 }
);

console.log(inventory.size, totalWeight, heaviestItem.name);

const ops = {
  add: (a, b) => a + b,
  subtract: (a, b) => a - b,
  multiply: (a, b) => a * b,
  divide: (a, b) => b !== 0 ? a / b : NaN,
};

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

const double  = (x) => ops.multiply(x, 2);
const addTen  = (x) => ops.add(x, 10);
const halve   = (x) => ops.divide(x, 2);
const subtractThree = (x) => ops.subtract(x, 3);

const transform = pipeline(double, addTen, halve, subtractThree);

const results = [5, 0, -4].map(transform);
console.log(results);

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(2);
  if (i === 1) return Number.isFinite(v) + " | " + Number.isNaN(v);
  if (i === 2) return Number.isFinite(v) + " | " + Number.MAX_SAFE_INTEGER;
  if (i === 3) return Object.is(v, -0) + " | " + (v === 0);
  if (i === 4) return v.toFixed(2) + " | " + v.toPrecision(4);
});

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