JavaScript

02 June 2026 08:30

CHALLENGE

const a = 9007199254740991n;
const b = BigInt(Number.MAX_SAFE_INTEGER);

console.log(a === b);
console.log(a + 1n);
console.log(typeof a);
console.log(a === 9007199254740991);

JavaScript

31 May 2026 14:40

Somewhere in Yerevan 🇦🇲😆

JavaScript

11 May 2026 08:30

CHALLENGE

class DatabaseError extends Error {
  constructor(message, code) {
    super(message);
    this.name = "DatabaseError";
    this.code = code;
  }
}

class ConnectionError extends DatabaseError {
  constructor(host) {
    super(`Failed to connect to ${host}`, 503);
    this.name = "ConnectionError";
    this.host = host;
  }
}

const err = new ConnectionError("db.server.io");

console.log([
  err instanceof ConnectionError,
  err instanceof DatabaseError,
  err instanceof Error,
  err.name,
  err.code,
  err.message,
].join(" | "));

JavaScript

10 May 2026 08:31

CHALLENGE

const items = [
  { name: "banana", price: 1.5, qty: 10 },
  { name: "apple",  price: 1.5, qty: 5  },
  { name: "cherry", price: 3.0, qty: 8  },
  { name: "date",   price: 2.0, qty: 8  },
];

const sorted = [...items].sort((a, b) => {
  if (a.price !== b.price) return a.price - b.price;
  if (a.qty   !== b.qty)   return b.qty   - a.qty;
  return a.name.localeCompare(b.name);
});

console.log(sorted.map(i => `${i.name}:${i.qty}`).join(", "));

JavaScript

09 May 2026 08:30

CHALLENGE

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));

JavaScript

07 May 2026 08:31

CHALLENGE

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);

JavaScript

05 May 2026 08:30

CHALLENGE

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);

JavaScript

03 May 2026 18:01

🤟 What’s Actually New in JavaScript (And What’s Coming Next)

If you don’t read the specs or endless posts about new language features, this is a great way to catch up. Most of the features are supported in Node, like Promise.try, Set union/intersection/difference, Array.fromAsync, and using, with others soon to land, like Math.sumPrecise and Map.getOrInsert (in Node 26).

Neciu Dan

JavaScript

02 May 2026 08:31

CHALLENGE

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);

JavaScript

30 April 2026 15:08

👀 Optique 1.0: Type-Safe Combinatorial CLI Parser

Build composable parsers for CLIs with type safety, type inference, and built-in shell completion support, plus config file integration and man page generation from the same definitions. v1.0 is the first stable release and Hong compares it to hongminhee/2026/optique-10-discriminated-unions-for-cli">Commander.js and explains why you'd use Optique.

Hong Minhee

JavaScript

29 April 2026 15:07

🤔 aube: A New Node.js Package Manager

Yes, another one! What’s noteworthy is it comes from the developer of mise, a tool that makes managing numerous languages so much easier. aube’s selling points are raw performance and being a drop-in replacement. Its defaults are also security-focused.

Jeff Dickey

JavaScript

28 April 2026 15:02

😃 Git 2.54 has been released with a couple of headline features:

• git history offers a new, easy way to edit commit messages or interactively split a commit into two.

• You can now define hooks in config files (whether in a repo, at user level, or even system level) rather than just in .git/hooks. You can also run multiple hooks for the same event in this way.

JavaScript

27 April 2026 15:02

🌟 Bun v1.3.13: Smarter Testing, Streaming Installs, and Less Memory

The Bun runtime has had a great run of releases, including last week’s v1.3.12 with built-in browser automation. Now, bun test gets numerous enhancements with --isolate, --parallel, --shard and --changed options for test env isolation, parallelization, and to run only test files affected by recent changes. The runtime now uses 5% less memory, bun install gets faster, and more.

Jarred Sumner

JavaScript

26 April 2026 15:01

😉 Evan You's State of Vue 2026 Talk

A month ago, Evan You (of Vue.js and VoidZero fame) gave his annual address. Less Vue-focused than usual (though Vapor Mode is “almost ready”), the talk focuses on Vite-ecosystem updates covering Vite 8, Vite+, and Void.

Evan You / Vue.js Amsterdam

JavaScript

25 April 2026 15:01

😮 HyperFrames: Write HTML and JavaScript to Create Videos

An open-source framework for creating and rendering videos with HTML and JavaScript. Essentially a simpler non-React alternative to Remotion. It includes a variety of built-in blocks/components for common video effects and elements, and can also composite existing video and audio clips. GitHub repo.

HeyGen

JavaScript

01 June 2026 08:31

CHALLENGE

const obj = {
  name: "Nikola",
  greetArrow: () => {
    return `Hello, ${this?.name ?? "stranger"}!`;
  },
  greetRegular() {
    return `Hello, ${this.name}!`;
  },
  greetNested() {
    const inner = () => `Hi, ${this.name}!`;
    return inner();
  }
};

console.log(obj.greetArrow());
console.log(obj.greetRegular());
console.log(obj.greetNested());

JavaScript

31 May 2026 08:31

CHALLENGE

const log = [];

const handler = {
  set(target, key, value) {
    log.push(`set:${key}=${value}`);
    target[key] = value;
    return true;
  },
  get(target, key) {
    log.push(`get:${key}`);
    return target[key];
  }
};

const state = new Proxy({}, handler);

state.count = 0;
state.count = state.count + 1;
state.count = state.count + 1;

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

JavaScript

10 May 2026 15:00

😮 html-to-text 10.0: Advanced HTML to Text Converter

Uses a variety of techniques to convert even complex HTML into plain text (but with some formatting, such as for tables). v10 brings the project up to modern standards.

KillyMXI

JavaScript

09 May 2026 15:05

🤟 Node.js 26.0 (Current) Released

It's here! Complete with the Temporal API enabled by default, V8 14.6 (say hello to map ‘upsert’ methods like Map.prototype.getOrInsert() and iterator sequencing with Iterator.concat()), plus Undici 8. v26 is the ‘Current’ cutting-edge release until October when it gets promoted to LTS.

Rafael Gonzaga

JavaScript

08 May 2026 08:30

CHALLENGE

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);

JavaScript

06 May 2026 08:31

CHALLENGE

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);
})();

JavaScript

04 May 2026 08:33

CHALLENGE

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(" | "));

JavaScript

03 May 2026 08:30

CHALLENGE

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();

JavaScript

01 May 2026 08:31

CHALLENGE

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);

JavaScript

30 April 2026 08:35

CHALLENGE

class ValidationError extends Error {
  constructor(message, field) {
    super(message);
    this.name = "ValidationError";
    this.field = field;
  }
}

class NetworkError extends ValidationError {
  constructor(message, field, statusCode) {
    super(message, field);
    this.name = "NetworkError";
    this.statusCode = statusCode;
  }
}

const err = new NetworkError("Not Found", "endpoint", 404);

console.log([
  err instanceof NetworkError,
  err instanceof ValidationError,
  err instanceof Error,
  err instanceof TypeError,
].join(", "));

JavaScript

29 April 2026 08:31

CHALLENGE

async function* paginate(items, pageSize) {
  for (let i = 0; i < items.length; i += pageSize) {
    const page = items.slice(i, i + pageSize);
    yield await Promise.resolve(page);
  }
}

async function* transform(source, fn) {
  for await (const chunk of source) {
    yield fn(chunk);
  }
}

async function run() {
  const data = [10, 20, 30, 40, 50, 60];

  const pages = paginate(data, 2);
  const mapped = transform(pages, (page) => page.map((x) => x * 2));

  const results = [];
  for await (const page of mapped) {
    results.push(page.reduce((a, b) => a + b, 0));
  }

  console.log(results);
}

run();

JavaScript

28 April 2026 08:30

CHALLENGE

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

const results = values.map((v, i) => {
  if (i === 0) return v.toFixed(2);
  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) + " " + Object.is(v, -0);
  if (i === 4) return v.toPrecision(4);
});

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

JavaScript

27 April 2026 08:32

CHALLENGE

const partial = (fn, ...presetArgs) => {
  return function partiallyApplied(...laterArgs) {
    return fn(...presetArgs, ...laterArgs);
  };
};

const calculateTax = (taxRate, discount, price) => {
  const discounted = price - (price * discount) / 100;
  return parseFloat((discounted + (discounted * taxRate) / 100).toFixed(2));
};

const withVAT = partial(calculateTax, 20);
const withVATandDiscount = partial(withVAT, 15);

console.log(withVAT(0, 100));
console.log(withVATandDiscount(200));
console.log(partial(calculateTax, 10, 5)(50));

JavaScript

26 April 2026 08:30

CHALLENGE

const counter = (function () {
  let count = 0;
  const history = [];

  return {
    increment(step = 1) {
      count += step;
      history.push(count);
      return this;
    },
    decrement(step = 1) {
      count -= step;
      history.push(count);
      return this;
    },
    getHistory: () => history,
    getCount: () => count,
  };
})();

counter.increment(5).increment(3).decrement(2);

console.log(counter.getCount(), counter.getHistory().join(" -> "));

JavaScript

25 April 2026 08:34

CHALLENGE

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}`);