TGViewer
Channel Public Channel
JavaScript

JavaScript

@javascript

A resourceful newsletter featuring the latest and most important news, articles, books and updates in the world of #javascript 🚀 Don't miss our Quizzes!

Let's chat: @nairihar
Open in Telegram
Subscribers
31.1K
Photos
1.2K
Videos
10
Links
895

Showing posts older than #2839 · Back to latest

Older Posts 20 shown
Post #2838 4.04K
  • 🤔 3
  • ❤ 2
  • 👍 2
  • 🔥 2
Post #2837 3.89K
CHALLENGE

const map = new Map([
  ['a', 1],
  ['b', 2],
  ['c', 3]
]);

const key = { id: 'key' };
map.set(key, 4);
map.set(key, 5);

const result = [];
result.push(map.get('a'));
result.push(map.get(key));
result.push(map.size);
result.push(map.has({ id: 'key' }));

console.log(result);
Post #2836 4.72K
🎉 JavaScript Turns 30 Years Old

Back in May 1995, a 33 year old Brendan Eich built the first prototype of JavaScript in just ten days, originally codenamed Mocha (and then LiveScript). On December 4, 1995, Netscape and Sun Microsystems officially announced 'JavaScript' in a press release as "an easy-to-use object scripting language designed for creating live online applications that link together objects and resources on both clients and servers."

Over thirty years, JavaScript has cemented its place at the heart of the Web platform, and more broadly in desktop apps, operating systems (e.g. Windows' use of React Native), mobile apps, and even on microcontrollers.
  • ❤ 16
  • 👍 4
  • 🤔 2
  • 🔥 1
Post #2834 3.81K
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;
  }
}

const emitter = new EventEmitter();
emitter.on('test', x => console.log(x * 2))
       .on('test', x => console.log(x + 5))
       .emit('test', 10);
Post #2833 3.8K
  • 🔥 5
  • 🤔 5
  • ❤ 1
Post #2832 3.82K
CHALLENGE

let obj1 = { name: 'Sarah' };
let obj2 = { name: 'Mike' };

obj1.ref = obj2;
obj2.ref = obj1;

let weakRef = new WeakRef(obj1);
let registry = new FinalizationRegistry((value) => {
  console.log(`Cleanup: ${value}`);
});

registry.register(obj1, 'obj1-cleaned');
obj1 = null;
obj2 = null;

console.log(weakRef.deref()?.name || 'undefined');
console.log('Script completed');
  • ❤ 1
Post #2831 3.81K
  • ❤ 3
  • 👍 1
Post #2830 3.93K
CHALLENGE

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

class Formatter {
  format(text) {
    return text.toUpperCase();
  }
}

class Service {
  constructor(logger, formatter) {
    this.logger = logger;
    this.formatter = formatter;
  }
  
  process(data) {
    const formatted = this.formatter.format(data);
    return this.logger.log(formatted);
  }
}

const service = new Service(new Logger(), new Formatter());
console.log(service.process('hello world'));
  • ❤ 4
  • 👍 3
  • 🤔 2
Post #2829 3.76K
  • 👍 9
  • ❤ 2
  • 🤔 2
Post #2828 3.9K
CHALLENGE

const data = '{"users": [{"name": "Sarah", "age": 25}, {"name": "Mike", "age": null}]}';

try {
  const parsed = JSON.parse(data);
  const result = parsed.users.map(user => {
    return user.age ?? 'unknown';
  });
  console.log(result.join(' - '));
} catch (error) {
  console.log('Parse error occurred');
}

const invalidJson = '{"name": "John", age: 30}';
try {
  JSON.parse(invalidJson);
  console.log('Success');
} catch {
  console.log('Invalid');
}
  • ❤ 12
Post #2826 3.98K
  • ❤ 5
  • 🤔 1
Post #2825 3.8K
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);
  • ❤ 3
Post #2824 3.8K
🗓 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
  • ❤ 10
  • 🤩 1
Post #2822 3.94K
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('-'));
  • ❤ 6
  • 👍 3
  • 🤔 1
Post #2821 3.43K
👀 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
  • 👍 5
  • ❤ 2
  • 🤔 1
Post #2819 3.83K
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);
  • ❤ 7
  • 🤔 2
Older posts →
Threads Profile ViewerView any public Threads profile without an account.Open ThreadLook →Writing with AI? Make it sound human.Metric37 rewrites AI drafts so they read naturally. Free AI detector, 1,500 words free.Try Metric37 →