JavaScript

😆

CHALLENGE

const handler = {
  get(target, prop, receiver) {
    if (prop in target) {
      return Reflect.get(target, prop, receiver) * 2;
    }
    return `missing:${prop}`;
  },
  set(target, prop, value) {
    if (typeof value !== "number") {
      throw new TypeError("Only numbers allowed");
    }
    return Reflect.set(target, prop, value * 10);
  },
  has(target, prop) {
    return prop.startsWith("x") ? false : prop in target;
  },
};

const store = new Proxy({ xRay: 5, score: 3 }, handler);

store.level = 4;

console.log(store.xRay);
console.log(store.score);
console.log(store.level);
console.log("xRay" in store);
console.log("score" in store);
console.log(store.missing);

😂

CHALLENGE

const inventory = [
  { name: "sword", type: "weapon", power: 85 },
  { name: "shield", type: "armor", power: 60 },
  { name: "bow", type: "weapon", power: 72 },
  { name: "helmet", type: "armor", power: 45 },
  { name: "dagger", type: "weapon", power: 91 },
];

const result = inventory
  .filter(item => item.type === "weapon")
  .map(item => ({ ...item, power: item.power * 1.1 }))
  .sort((a, b) => b.power - a.power)
  .reduce((acc, item, index) => {
    acc[index === 0 ? "best" : "rest"] ??= [];
    if (index === 0) acc.best = item.name;
    else acc.rest.push(item.name);
    return acc;
  }, {});

console.log(result.best, result.rest);

🗓 FullCalendar 7.0: A Full Sized JavaScript Calendar A Google Calendar-style experience for your own apps. Works with React, Vue and Angular (v7.0 adds Angular 22 support), but can be used with plain JavaScript. Here’s a demo where you can play with the themes and styling approaches. MIT licensed with commercial extensions. FullCalendar LLC

🤖 Read more

😃 A developer code-golfed a signal implementation to just 33 bytes (above). I had to stare at it for a solid minute before it clicked, but mercifully, a Redditor breaks down exactly what's going on.

CHALLENGE

function highlight(strings, ...values) {
  return strings.reduce((result, str, i) => {
    const value = values[i - 1];
    const formatted =
      typeof value === "number"
        ? `[${value.toFixed(2)}]`
        : `<${String(value).toUpperCase()}>`;
    return result + formatted + str;
  });
}

const item = "sword";
const qty = 3;
const price = 9.5;

const output = highlight`You bought ${qty} ${item}s for $${price} each.`;
console.log(output);

😂

CHALLENGE

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

async function processQueue(items) {
  const results = [];

  await items.reduce(async (prevPromise, item) => {
    await prevPromise;
    await delay(0);
    results.push(item * 2);
  }, Promise.resolve());

  return results;
}

processQueue([1, 2, 3, 4])
  .then((data) => console.log("Result:", data))
  .catch((err) => console.log("Error:", err.message));

Promise.resolve()
  .then(() => console.log("Microtask A"))
  .then(() => console.log("Microtask B"));

💻 Desktop Apps With deno desktop Deno 2.9 (or the 'canary' build now) can turn JavaScript projects into self-contained apps on macOS, Windows, and Linux. Unlike Electron, you can opt to use the default OS WebView or a bundled Chromium backend, plus you get cross-compilation and automatic support for apps built on frameworks like Next.js and SvelteKit. The Deno Project

CHALLENGE

function makeCounter(start = 0, step = 1) {
  let count = start;
  const history = [];

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

const counter = makeCounter(10, 3);
counter.increment().increment().decrement();

console.log(counter.getCount());
console.log(counter.getHistory());

🤖 Eve: A Next.js-Style Framework for Building Agents A new framework from Vercel that provides Next.js-esque structure for building AI-powered agents using TypeScript and Markdown. It's quite Vercel-flavored by default, but I found you can run it entirely independently of Vercel with a few settings tweaks and your own keys. Project homepage. Vercel

🌲 Node.js 26.4 Adds Package Maps A minor release whose headline feature is the (experimental) implementation of package maps (which let Node resolve packages from a static JSON file rather than walking node_modules). Matteo Collina’s node:vfs subsystem also begins to make an appearance. Antoine du Hamel