JavaScript

CHALLENGE

const flags = {
  READ:    0b0001,
  WRITE:   0b0010,
  EXECUTE: 0b0100,
  DELETE:  0b1000,
};

const userPermissions  = flags.READ | flags.WRITE | flags.EXECUTE;
const adminPermissions = userPermissions | flags.DELETE;

const canDelete  = (adminPermissions & flags.DELETE)  !== 0;
const canExecute = (userPermissions  & flags.EXECUTE) !== 0;
const readOnly   = userPermissions   ^ flags.WRITE;

console.log(canDelete, canExecute, readOnly, adminPermissions >> 1);

😱 Bun's Zig-to-Rust porting saga continues, but what about Node...? The Rust-based rewrite of Bun has been merged, though there are questions over the quality of the AI-ported code. Matteo Collina and Luca Maraschi got together to 😉 discuss the story and speculate whether Node could follow...

CHALLENGE

const config = {
  db: { host: "localhost", port: 5432 },
  cache: { ttl: 300 },
};

Object.freeze(config);

config.debug = true;
config.db.port = 9999;
config.cache = { ttl: 600 };

const sealed = Object.seal({ version: "1.0", meta: { build: 42 } });

sealed.version = "2.0";
sealed.author = "devteam";
sealed.meta.build = 99;

console.log(
  config.debug,
  config.db.port,
  config.cache.ttl,
  sealed.version,
  sealed.author,
  sealed.meta.build
);

🤟 An Official Codemod to Migrate from Axios to fetch A codemod (used via npx codemod) that transforms code using Axios to leverage the WHATWG Fetch API, which is now natively available in Node.js. For some reason they don’t link to it in the post, but it’s here if you want to try it out (and here’s the underlying code). Augustin Mauroy

CHALLENGE

const prefix = "get";
const suffix = "Name";

const registry = {
  [`${prefix}Full${suffix}`]: function () {
    return `${this.first} ${this.last}`;
  },
  [`${prefix}Short${suffix}`]: function () {
    return this.first[0] + ". " + this.last;
  },
};

const person = {
  first: "Leonardo",
  last: "Fibonacci",
  ...registry,
};

const key = ["Full", "Short"][1];
console.log(person[`${prefix}${key}${suffix}`]());

🤟 A Fresh Chapter and New Look for Express For a while, Node’s long-standing web framework, Express.js, was looking a bit stale and projects like Fastify were beginning to carry the torch, but a major reboot that began in 2024 brought Express back to the fore. Now Express’s brand, website, and docs have time-travelled to 2026 too. Sebastian Beltran

CHALLENGE

const tag = (strings, ...values) => {
  return strings.reduce((result, str, i) => {
    const value = values[i - 1];
    const transformed =
      typeof value === "number" ? `[${value ** 2}]` : `{${value}}`;
    return result + transformed + str;
  });
};

const name = "Sofia";
const score = 4;
const level = "gold";

const output = tag`Player: ${name}, Score: ${score}, Rank: ${level}`;
console.log(output);

✌️ Andrea Giammarchi proposes JSONRegistry (above), an alternative to JSON that lets you define a registry for serializing and reviving custom/branded types.

CHALLENGE

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

async function* asyncGen() {
  yield await delay(10, "alpha");
  yield await delay(10, "beta");
  yield await delay(10, "gamma");
}

async function run() {
  const results = [];

  const gen = asyncGen();
  const [first, , third] = await Promise.all([
    gen.next(),
    gen.next(),
    gen.next()
  ]);

  results.push(first.value, third.value);

  const p1 = Promise.resolve("x").then(v => v + "1");
  const p2 = Promise.reject("err").catch(e => e + "2");

  results.push(...(await Promise.all([p1, p2])));
  console.log(results);
}

run();

👀 Orval: Generate Type-Safe Clients from OpenAPI/Swagger Specs Given a valid OpenAPI v3 or Swagger v2 spec, generate models, requests, hooks, and mocks for React, Vue, Svelte, Solid, and Hono apps, or even plain fetch. Victor Bury

CHALLENGE

const str = "JavaScript is Awesome!";

const result = str
  .split(" ")
  .map((word, i) => 
    i % 2 === 0
      ? word.toUpperCase()
      : word.toLowerCase()
  )
  .join("-");

const reversed = result
  .split("")
  .reduce((acc, char) => char + acc, "");

console.log(reversed);

🤖 Mark Erikson's Agent Setup, Workflow, and Tools Mark, well known for maintaining Redux and creating Redux Toolkit, goes deep into his daily development workflow, including his use of OpenCode (an open source JavaScript-powered coding agent), how he manages his knowledge base, tasks, and more. Mark Erikson

CHALLENGE

const createModule = (() => {
  const privateCache = new WeakMap();

  return function(name) {
    const state = { name, version: 1, active: true };
    privateCache.set(state, { accessCount: 0 });

    return {
      getInfo() {
        const meta = privateCache.get(state);
        meta.accessCount++;
        return `${state.name}@v${state.version}`;
      },
      getAccessCount() {
        return privateCache.get(state).accessCount;
      },
      upgrade() {
        state.version++;
        return this;
      }
    };
  };
})();

const mod = createModule("auth");
mod.upgrade().upgrade();
console.log(mod.getInfo());
console.log(mod.getAccessCount());