JavaScript

❓ TermDOM: Build Terminal UIs with HTML, CSS and the DOM Like the look of Ink but don't like React? TermDOM implements a DOM, cascade and layout engine that paints to the terminal, so you can write a TUI with HTML and CSS. Pure JS, no native or WASM dependencies, and the official TodoMVC runs with only a stylesheet swap. Early days, but I like the idea! Brian Kim

CHALLENGE

function curry(fn) {
  return function curried(...args) {
    if (args.length >= fn.length) {
      return fn.apply(this, args);
    }
    return (...more) => curried.apply(this, args.concat(more));
  };
}

function add(a, b, c = 10) {
  return a + b + c;
}

const curriedAdd = curry(add);
console.log(`${curriedAdd(1)(2)} ${curriedAdd(1,2,3)} ${curriedAdd(4)(5,6)}`);

The js1024 code golfing contest is over and we have three winners! Skydreams, a Super Monkey Ball-like experience, came in first place. You can read the readable and minified source if you want to see the techniques used.

CHALLENGE

function combine(a, b = 10, ...rest) {
  return JSON.stringify([a, b, rest]);
}
const inputs = [1, undefined, 3, 4, 5];
console.log(combine(...inputs));

👀 Migrating a Large Flow Monorepo to TypeScript Over several years, Yelp moved 1.4 million lines off Flow, and this writeup is more useful as a guide to running any long migration than as a Flow story. It was a big win on its own terms, with type coverage up from 83% to 96%. Shawn Walton (Yelp)

CHALLENGE

const key = 'greet';
const name = 'world';
const obj = {
  name,
  [key]() { return `Hello, ${this.name}`; },
  [`${key}Arrow`]: () => `Hello, ${this?.name}`,
};
console.log(`${obj.greet()} | ${obj.greetArrow()}`);

CHALLENGE

const obj = { a: { b: null }, getVal: null };
let counter = 0;
function sideEffect() {
  counter++;
  return counter;
}
const result = obj?.a?.b?.[sideEffect()] ?? 'default1';
const result2 = obj.getVal?.(sideEffect()) ?? 'default2';
const result3 = obj?.a?.c?.d ?? sideEffect();
console.log(result, result2, result3, counter);

Did you know JavaScript supports a third type of comment (beyond // and /* */)? 😉 Mat Marquis shows off hashbang comments in a short YouTube video. And yes, they're in the language spec!

CHALLENGE

function test() {
  try {
    console.log(y);
  } catch (e) {
    return e.constructor.name;
  }
}

let result1 = test();
let y = 'hoisted';

console.log(result1, typeof y, y);

👀 anydoc: Convert 14 Document Formats into Markdown A Rust-powered library (with Node.js and WASM bindings) that converts Word, PowerPoint, Excel, OpenDocument, RTF, EPUB, CSV, and PDF documents into Markdown. I tried it on a 1,600 page PDF and it took less than 2 seconds. There's also an in-browser demo to try it out. GitHub repo. Firecrawl

CHALLENGE

const arr = [1, 2, 3, 4, 5];
arr[Symbol.iterator] = function* () {
  for (let i = 0; i < 3; i++) yield arr[i] * 2;
};
console.log([...arr], JSON.stringify(arr));

🤟 Node.js 26.7.0 (Current) Released Landing just two days after 26.6, coverage reports can now include files your tests didn't touch with --test-coverage-include-all, FFI and SQLite pick up crash fixes, and Perfetto tracing support lands, though you'll need a custom build to use it. Antoine du Hamel

CHALLENGE

class Money {
  #amount;
  constructor(amount) { this.#amount = amount; }
  [Symbol.toPrimitive](hint) {
    if (hint === 'number') return this.#amount;
    if (hint === 'string') return `$${this.#amount}`;
    return `Money(${this.#amount})`;
  }
}
const m = new Money(42);
console.log(`${m}`, m + 8, m == 42);