JavaScript

15 November 2025 14:03

😮 Render.js: A Raytracing Renderer with RenderMan Format Support

Created at Pixar in the 80s, the RenderMan Interface Specification was an early API for building 3D scenes. Anders has been building a Node-based, 90s-style renderer for the format “as a stroll down amnesia lane” in pure JavaScript.

Anders Brownworth

JavaScript

13 November 2025 07:31

CHALLENGE

const obj = { count: 0 };
const arr = [obj, obj, obj];

function increment(item) {
  item.count++;
  return item;
}

const results = arr.map(increment);
console.log(obj.count);
console.log(results[0] === results[1]);
console.log(results.length);
console.log(arr[0].count);

JavaScript

12 November 2025 07:31

CHALLENGE

class EventEmitter {
  constructor() {
    this.events = {};
  }
  
  on(event, callback) {
    this.events[event] = this.events[event] || [];
    this.events[event].push(callback);
    return this;
  }
  
  emit(event, data) {
    if (this.events[event]) {
      this.events[event].forEach(cb => cb(data));
    }
    return this;
  }
}

class Logger {
  log(msg) { console.log(`[LOG]: ${msg}`); }
}

class DataProcessor {
  constructor(emitter, logger) {
    this.emitter = emitter;
    this.logger = logger;
    this.emitter.on('process', (data) => {
      this.logger.log(data.toUpperCase());
    });
  }
  
  process(data) {
    this.emitter.emit('process', data);
  }
}

const emitter = new EventEmitter();
const logger = new Logger();
const processor = new DataProcessor(emitter, logger);

processor.process('hello world');
emitter.emit('process', 'composition rocks');

JavaScript

25 October 2025 08:33

CHALLENGE

const Maybe = {
  of: (value) => ({ value, map: f => value == null ? Maybe.nothing() : Maybe.of(f(value)) }),
  nothing: () => ({ value: null, map: () => Maybe.nothing() })
};

const result = Maybe.of(5)
  .map(x => x * 2)
  .map(x => x > 15 ? null : x)
  .map(x => x + 1)
  .map(x => x.toString());

console.log(result.value);

JavaScript

24 October 2025 08:31

CHALLENGE

function Vehicle(type) {
  this.type = type;
}

Vehicle.prototype.describe = function() {
  return `This is a ${this.type}`;
};

function Car(brand) {
  Vehicle.call(this, 'car');
  this.brand = brand;
}

Car.prototype = Object.create(Vehicle.prototype);
Car.prototype.constructor = Car;

Car.prototype.describe = function() {
  return Vehicle.prototype.describe.call(this) + ` made by ${this.brand}`;
};

const tesla = new Car('Tesla');
console.log(tesla.describe());
console.log(tesla.constructor.name);

JavaScript

21 October 2025 08:31

CHALLENGE

const numbers = [1, 2, 3, 4, 5];

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

const multiply = (x) => (y) => x * y;
const add = (x) => (y) => x + y;
const square = (x) => x * x;

const transform = pipeline(
  multiply(2),
  add(3),
  square
);

const result = numbers.map(transform);
console.log(result);

JavaScript

19 October 2025 08:31

CHALLENGE

const wm = new WeakMap();
const obj1 = {};
const obj2 = {};
const obj3 = obj1;

wm.set(obj1, 'first');
wm.set(obj2, 'second');
wm.set(obj3, 'third');

console.log(wm.get(obj1));
console.log(wm.get(obj2));
console.log(wm.get(obj3));
console.log(wm.has(obj1));
console.log(wm.size);

JavaScript

17 October 2025 08:31

CHALLENGE

const a = 9007199254740991n;
const b = BigInt(9007199254740991);
const c = 9007199254740992;
const d = BigInt(9007199254740992);

console.log(a === b);
console.log(Number(a) === c);
console.log(c === Number.MAX_SAFE_INTEGER + 1);
console.log(d > a);
console.log(typeof (a + 1n));
console.log(Number(d) === c);

JavaScript

16 October 2025 08:30

CHALLENGE

class Observable {
  constructor(subscriber) {
    this.subscriber = subscriber;
  }
  
  subscribe(observer) {
    return this.subscriber(observer);
  }
  
  map(fn) {
    return new Observable(observer => {
      return this.subscribe({
        next: value => observer.next(fn(value)),
        error: err => observer.error(err),
        complete: () => observer.complete()
      });
    });
  }
}

const source = new Observable(observer => {
  observer.next(1);
  observer.next(2);
  observer.complete();
});

const doubled = source.map(x => x * 2);
doubled.subscribe({
  next: value => console.log(value),
  complete: () => console.log('done')
});

JavaScript

15 October 2025 08:32

CHALLENGE

class Calculator {
  static multiply(a, b) {
    return a * b;
  }
  
  static add = (a, b) => {
    return a + b;
  }
}

class ScientificCalculator extends Calculator {
  static multiply(a, b) {
    return super.multiply(a, b) * 2;
  }
}

console.log(Calculator.multiply(3, 4));
console.log(ScientificCalculator.add(5, 6));
console.log(ScientificCalculator.multiply(2, 3));

JavaScript

14 October 2025 08:31

CHALLENGE

const obj = {
  name: 'Sarah',
  greet() {
    return `Hello, ${this.name}`;
  },
  delayedGreet() {
    const fn = function() {
      return this.greet();
    };
    return fn.call(this);
  }
};

const result = obj.delayedGreet();
console.log(result);

JavaScript

12 October 2025 08:34

CHALLENGE

class Observable {
  constructor(subscribe) {
    this.subscribe = subscribe;
  }
  
  map(fn) {
    return new Observable(observer => {
      return this.subscribe({
        next: value => observer.next(fn(value)),
        error: err => observer.error(err),
        complete: () => observer.complete()
      });
    });
  }
}

const source = new Observable(observer => {
  observer.next(1);
  observer.next(2);
  observer.complete();
});

const doubled = source.map(x => x * 2);
doubled.subscribe({
  next: value => console.log(value),
  complete: () => console.log('done')
});

JavaScript

10 October 2025 15:00

🤟 A very fast SIMD-first image comparison library (with nodejs API)

JavaScript

09 October 2025 14:00

😮 New Era for React = Stronger JavaScript Ecosystem 💙

We're thrilled that React is coming under the The Linux Foundation to create the React Foundation.

React doesn’t live in isolation - It works alongside Node.js, Electron, Webpack, and more. A dedicated foundation means more collaboration, security, and sustainability across the ecosystem.

OpenJS Foundation

JavaScript

08 October 2025 15:57

🤟 15 Recent Node Features That Can Replace Popular npm Packages

Many features that once required third-party packages are now built into the runtime itself. Here’s a look at some of the most notable that you may want to experiment with, prior to reducing unnecessary dependencies.

Lizz Parody

JavaScript

14 November 2025 14:28

👀 Umami 3.0: A Self-Hosted, Privacy-Focused Google Analytics Alternative

Think something like Plausible or Google Analytics, but built in Node and ready for you to host yourself. Here’s the full feature list. MIT licensed but also available as a paid hosted service.

Umami Software, Inc.

JavaScript

12 November 2025 14:05

🤟 Node.js Security Best Practices

Did you know the Node.js project maintains a page about security best practices organized around how to mitigate ten of the most significant vectors? Topics include networking weaknesses, timing attacks, supply chain attacks, and the monkey patching of intrinsics.

Node Documentation

JavaScript

11 November 2025 07:31

CHALLENGE

class CustomError extends Error {
  constructor(message) {
    super(message);
    this.name = 'CustomError';
  }
}

try {
  throw new CustomError('Something went wrong');
} catch (e) {
  console.log(e instanceof Error);
  console.log(e instanceof CustomError);
  console.log(e.constructor.name);
  console.log(e.name);
}

JavaScript

24 October 2025 15:41

A minimal CheatEngine implementation built with Rust and a terminal UI.

Do you think it’s possible to create something similar with JavaScript?

JavaScript

21 October 2025 19:44

🤟 Node.js v25.0.0 (Current) Released

The latest cutting edge version of Node has arrived with Web Storage enabled by default, JSON.stringify perf improvements, a new --allow-net option in the permission model, built-in Uint8Array base64/hex conversion, and WebAssembly and JIT optimizations. As shown in the diagram above, this means Node 24 will soon be promoted to being the 'active' LTS release and Node 22 will enter its 'maintenance' LTS phase.

Rafael Gonzaga

JavaScript

20 October 2025 08:33

CHALLENGE

const data = '{"name": "Maria", "age": 25, "skills": ["JavaScript", "Python"]}';

try {
  const parsed = JSON.parse(data);
  const modified = {
    ...parsed,
    age: parsed.age + 5,
    skills: [...parsed.skills, "TypeScript"]
  };
  
  const serialized = JSON.stringify(modified, null, 0);
  const reparsed = JSON.parse(serialized);
  
  console.log(reparsed.skills.length);
  console.log(typeof reparsed.age);
} catch (error) {
  console.log('Parse error');
}

JavaScript

18 October 2025 08:31

CHALLENGE

const userInput = "<script>alert('xss')</script>";
const sanitized = userInput
  .replace(/</g, '&lt;')
  .replace(/>/g, '&gt;')
  .replace(/"/g, '&quot;')
  .replace(/'/g, '&#x27;');

const credentials = {
  username: 'admin',
  password: 'secret123'
};

const safeLog = (obj) => {
  const { password, ...safe } = obj;
  return JSON.stringify(safe);
};

console.log(sanitized);
console.log(safeLog(credentials));

JavaScript

16 October 2025 15:05

👍 The Firefox team has put together a way for you to give input on which Interop proposals matter the most to you (above). Go to the Interop Feature Ranking site (GitHub account required) and drag the web platform features that matter most for you to the top.

JavaScript

15 October 2025 15:05

👀 Viz.js 3.20: Work with Graphviz in the Browser

Graphviz is a suite of open source graph drawing tools of over 30 years’ vintage. Viz.js is a WebAssembly Graphviz build that brings its functionality into the browser. GitHub repo.

Michael Daines

JavaScript

14 October 2025 15:02

📥 The Birth of Prettier

The author takes us back ten years to the genesis of Prettier, the popular opinionated, deterministic code formatter he co-created with James Long. Prettier effectively introduced and popularized the practice of fully-automated AST-based code formatting in the JavaScript ecosystem.

Christopher Chedeau (Vjeux)

JavaScript

13 October 2025 14:04

💌 Vite: The Documentary

From the same creators of the fantastic 😉 Node.js, 😉 Angular and 😉 React documentaries comes an up to date look at Vite, the build tool that has taken the JavaScript ecosystem by storm in recent years. Many luminaries make an appearance to tell their stories, including Evan You, Rich Harris, and Ryan Carniato. (39 minutes.)

CultRepo

JavaScript

11 October 2025 08:32

CHALLENGE

const obj = {
  name: 'Sarah',
  greet: () => {
    console.log(`Hello, ${this.name}`);
  },
  sayHi: function() {
    const inner = () => {
      console.log(`Hi, ${this.name}`);
    };
    inner();
  }
};

obj.greet();
obj.sayHi();

JavaScript

10 October 2025 08:32

CHALLENGE

const ws = new WeakSet();
const obj1 = { name: 'first' };
const obj2 = { name: 'second' };
const obj3 = obj1;

ws.add(obj1);
ws.add(obj2);
ws.add(obj3);

console.log(ws.has(obj1));
console.log(ws.has(obj3));
console.log(ws.has({ name: 'first' }));
console.log(ws.size);

JavaScript

09 October 2025 08:33

CHALLENGE

function mystery(arr, depth = 0) {
  if (arr.length <= 1) return arr;
  
  const mid = Math.floor(arr.length / 2);
  const left = mystery(arr.slice(0, mid), depth + 1);
  const right = mystery(arr.slice(mid), depth + 1);
  
  const result = [];
  let i = 0, j = 0;
  
  while (i < left.length && j < right.length) {
    result.push(left[i] <= right[j] ? left[i++] : right[j++]);
  }
  
  return result.concat(left.slice(i)).concat(right.slice(j));
}

const arr = [3, 1, 4, 1, 5];
console.log(mystery(arr));

JavaScript

08 October 2025 08:34

CHALLENGE

const multiply = (a) => (b) => (c) => a * b * c;

const step1 = multiply(2);
const step2 = step1(3);
const result1 = step2(4);

const partialMult = multiply(5)(6);
const result2 = partialMult(7);

const directResult = multiply(1)(8)(9);

console.log(result1);
console.log(result2);
console.log(directResult);
console.log(typeof step1);
console.log(typeof partialMult);