JavaScript

02 December 2025 14:05

🥶 TSDiagram: Diagrams as Code with TypeScript

Draft diagrams quickly with TypeScript. Define your data models through top-level type aliases and interfaces and it automatically lays out the nodes in an efficient way. GitHub repo.

Andrei Neculaesei

JavaScript

01 December 2025 14:04

🗓 FullCalendar: A Full Sized JavaScript Calendar Control

Get a Google Calendar-style experience in your own apps. Has connectors for React, Vue and Angular, but can be used with plain JavaScript too. The base version is MIT licensed, but there’s a commercial version too with extra features.

Adam Shaw

JavaScript

30 November 2025 14:03

👀 The Performance Inequality Gap in 2026

Esteemed browser and Web standards expert Alex Russell looks at the state of client-side Web performance, what sort of bandwidth you should be taking into account, what devices people are using, and warns against ever-growing JavaScript bundle sizes. A lot of data here.

Alex Russell

JavaScript

29 November 2025 14:00

✌️ Over 150 Algorithms and Data Structures Demonstrated in JS

Examples of many common algorithms (e.g. bit manipulation, Pascal’s triangle, Hamming distance) and data structures (e.g. linked lists, tries, graphs) with explanations. Available in eighteen other written languages too.

Oleksii Trekhleb et al.

JavaScript

28 November 2025 14:04

😆

JavaScript

26 November 2025 14:35

🔒 OWASP (Open Worldwide Application Security Project) has released its list of the top ten web application security threats in 2025.

JavaScript

24 November 2025 14:33

👀 imgui-react-runtime: React + Dear ImGui + Static Hermes

When the author teased a demo of this on X a few weeks ago, I wasn’t sure if it would get released, but here it is. A new way to put together native apps using React and the popular lightweight GUI library Dear ImGui.

Tzvetan Mikov

JavaScript

23 November 2025 14:33

😉 The State of Node.js in 2025, Explained

A thirty-minute talk from JSNation earlier this year where TSC member Matteo Collina presented an update on Node’s still-growing popularity, release schedule, security, recent performance enhancements, the permissions system, and more.

GitNation

JavaScript

22 November 2025 14:32

✌️ JavaScript Engines Zoo: Learn About Over 100 JS Engines

I’m a sucker for a big table of data and this is about as big as it gets when it comes to JavaScript engines. See how various engines compare, sort them by performance, or click on an engine’s name to learn more about its development, history, and end users. The project’s repo also has Dockerfiles for trying each of them out.

Ivan Krasilnikov

JavaScript

21 November 2025 14:04

👀 Vibe Coding ≠ AI-Assisted Coding

Most people don't know the difference...

Laszlo Horvath

JavaScript

20 November 2025 14:33

👀 In Your URL is Your State, Ahmad Alfy looks at the 'overlooked power' and elegance of using the URL's various components for representing state.

JavaScript

19 November 2025 14:32

🎹 Perspective 4.0: High Performance Analytics and Data Visualization Component

Originally built by JP Morgan, this data visualization component, built in C++ and compiled to WebAssembly, is well-suited for large and real-time streaming datasets. The demo on the homepage lets you try visualization types at up to 1000 changes per second. v4.0 sees the project move to the OpenJS Foundation.

OpenJS Foundation

JavaScript

18 November 2025 14:40

😉 The Talk Videos from CascadiaJS 2025

CascadiaJS took place a month ago and the talk videos have been gradually rolling out onto YouTube. You can learn more about TanStack with Jack Herrington, the origin story of JavaScript with Annie Sexton, the Web Monetization API with Ioana Chiorean, and more.

CascadiaJS

JavaScript

17 November 2025 14:07

🤩 The Inner Workings of JavaScript Source Maps

Ever wondered how devtools can magically turn mangled, minified JavaScript back into readable source while debugging? Zero magic; that’s a source map doing its job. But how do source maps actually work under the hood?

Manoj Vivek

JavaScript

16 November 2025 14:29

🇯🇵 Fancy writing JavaScript in Japanese (above)? Say こんにちは to KokoScript.

JavaScript

02 December 2025 07:34

CHALLENGE

const arr = [1, 2, 3];
const obj = { valueOf: () => 4, toString: () => '5' };
const result1 = arr + obj;
const result2 = +obj;
const result3 = String(obj);
const result4 = obj == 4;
const result5 = obj === 4;
console.log(`${result1}|${result2}|${result3}|${result4}|${result5}`);
const weird = [] + [] + 'hello';
const weirder = [] + {} + [];
const weirdest = {} + [] + {};
console.log(`${weird}|${weirder}|${weirdest}`);
const final = !!'0' + !!'' + !!null + !!undefined;
console.log(final);

JavaScript

01 December 2025 07:32

CHALLENGE

class SimpleObservable {
  constructor(subscribeFn) {
    this.subscribeFn = subscribeFn;
  }
  
  subscribe(observer) {
    return this.subscribeFn(observer);
  }
}

const obs = new SimpleObservable(observer => {
  observer.next('first');
  observer.next('second');
  observer.complete();
});

const results = [];
obs.subscribe({
  next: val => results.push(val),
  complete: () => results.push('done')
});

console.log(results.join('-'));

JavaScript

30 November 2025 07:32

CHALLENGE

const original = {
  name: 'Sarah',
  hobbies: ['reading', 'coding'],
  address: { city: 'Portland', zip: 97201 }
};

const shallow = { ...original };
const deep = JSON.parse(JSON.stringify(original));

shallow.name = 'Emma';
shallow.hobbies.push('hiking');
shallow.address.city = 'Seattle';

deep.hobbies.push('swimming');
deep.address.zip = 98101;

console.log(original.hobbies.length, original.address.city);

JavaScript

29 November 2025 07:32

CHALLENGE

const user = {
  profile: {
    settings: {
      theme: 'dark',
      notifications: null
    }
  }
};

const result1 = user?.profile?.settings?.theme;
const result2 = user?.profile?.settings?.notifications?.email;
const result3 = user?.profile?.preferences?.language ?? 'en';
const result4 = user?.profile?.settings?.notifications?.push?.('test');

console.log(result1, result2, result3, result4);

JavaScript

27 November 2025 14:13

📸 Google Announces Angular v21

The Google team has gone all out with this significant release of its popular JavaScript framework. They’ve put together a retro game-themed adventure-based tour of what’s new, along with top notch videos showing off features like its new signal-based approach to forms, MCP server for AI-powered workflows, library of headless components focused on accessibility, and even a new ‘Angular AI Tutor’ to get up to speed.

Google

JavaScript

25 November 2025 14:34

😮 vis-timeline 8.4 – Interactive control to visualize data across time, as shown above. Numerous examples here.

JavaScript

24 November 2025 07:30

CHALLENGE

console.log(typeof myFunction);
console.log(typeof myVar);
console.log(typeof myLet);
console.log(typeof myConst);

var myVar = 'hello';
let myLet = 'world';
const myConst = 'test';

function myFunction() {
  return 'hoisted';
}

console.log(myFunction());
console.log(myVar);

JavaScript

22 November 2025 21:20

✌️ This week's TC39 meeting: The Ecma TC39 committee (the group behind the design of ECMAScript / JavaScript) met up for the 111th time this week (seen above) to discuss language proposals. The meeting notes won't be published for a few weeks, but several proposals did see some progress:

- Iterator Sequencing progressed to stage 4.

- Joint Iteration, Iterator Join, and Await dictionary of Promises go stage 2.7.

- The Intl Unit Protocol also reached stage 1 to provide a way to annotate quantities with the units being measured.

- Typed Array Find Within progressed to stage 1. Think a native indexOf-type method for TypedArrays.

Note: Learn more about what the TC39 stages mean here.

JavaScript

22 November 2025 07:31

CHALLENGE

const Flyable = {
  fly() { return 'flying'; }
};

const Swimmable = {
  swim() { return 'swimming'; }
};

function applyMixins(target, ...mixins) {
  mixins.forEach(mixin => {
    Object.assign(target.prototype, mixin);
  });
}

class Bird {}
class Fish {}

applyMixins(Bird, Flyable, Swimmable);
applyMixins(Fish, Swimmable);

const eagle = new Bird();
const shark = new Fish();

console.log(eagle.swim());
console.log(shark.fly?.() || 'undefined method');

JavaScript

21 November 2025 07:32

CHALLENGE

const target = { name: 'Sarah', age: 25 };

const handler = {
  get(obj, prop) {
    if (prop in obj) {
      return obj[prop];
    }
    return `Property '${prop}' not found`;
  },
  set(obj, prop, value) {
    obj[prop] = value.toString().toUpperCase();
    return true;
  }
};

const proxy = new Proxy(target, handler);
proxy.city = 'boston';
console.log(proxy.name);
console.log(proxy.city);
console.log(proxy.country);

JavaScript

20 November 2025 07:32

CHALLENGE

console.log('1');

setTimeout(() => console.log('2'), 0);

Promise.resolve().then(() => console.log('3'));

queueMicrotask(() => console.log('4'));

setTimeout(() => {
  console.log('5');
  Promise.resolve().then(() => console.log('6'));
}, 0);

console.log('7');

JavaScript

19 November 2025 07:32

CHALLENGE

const target = { name: 'Sarah', age: 25 };
const handler = {
  get(obj, prop) {
    if (prop === 'info') {
      return `${obj.name} is ${obj.age}`;
    }
    return Reflect.get(obj, prop);
  },
  has(obj, prop) {
    return prop !== 'age' && Reflect.has(obj, prop);
  }
};
const proxy = new Proxy(target, handler);
console.log(proxy.info);
console.log('age' in proxy);
console.log('name' in proxy);

JavaScript

18 November 2025 07:31

CHALLENGE

const wm = new WeakMap();
const obj1 = { name: 'first' };
const obj2 = { name: 'second' };

wm.set(obj1, 'value1');
wm.set(obj2, 'value2');

const keys = [];
for (let key of wm) {
  keys.push(key);
}

console.log(keys.length);
console.log(wm.has(obj1));
console.log(wm.get(obj2));

JavaScript

17 November 2025 07:31

CHALLENGE

const user = { name: 'Sarah', age: 28 };
const greeting = 'Hello';
const template = `${greeting}, ${user.name}! You are ${user.age} years old.`;

function createMessage(strings, ...values) {
  return strings.reduce((result, string, i) => {
    return result + string + (values[i] ? `[${values[i]}]` : '');
  }, '');
}

const tagged = createMessage`Welcome ${user.name}, age: ${user.age}!`;
console.log(template);
console.log(tagged);

JavaScript

16 November 2025 07:30

CHALLENGE

const data = '{"name":"Sarah","age":25,"skills":["JavaScript","Python"]}'
const parsed = JSON.parse(data)
const stringified = JSON.stringify(parsed, null, 0)
const reparsed = JSON.parse(stringified)

try {
  const invalid = '{name:"John","incomplete":}'
  JSON.parse(invalid)
} catch (e) {
  console.log(e.name)
}

console.log(typeof parsed.age)
console.log(reparsed.skills.length)
console.log(JSON.stringify({a: undefined, b: null, c: 0}))