JavaScript

CHALLENGE

function* genFunc() {
  yield Symbol('A');
  yield new Function('return this')();
}

const obj = { key: genFunc().next().value };
obj.key = genFunc().next().value;

console.log(obj.key === globalThis);

CHALLENGE

let obj1 = { key: 'value1' };
let obj2 = { key: 'value2' };

const map = new Map();
const weakMap = new WeakMap();

map.set(obj1, 'mapValue');
weakMap.set(obj2, 'weakMapValue');

obj1 = null;  // Changing reference
obj2 = null;  // Changing reference

console.log(map.has(obj1));
console.log(weakMap.has(obj2));

✌️ SOME UPDATES JavaScript Weekly

✌️ Promises from the Ground Up Josh notes that in order to truly understand promises, a fundamental part of modern JS development, we need “a surprisingly deep understanding of how JavaScript works and what its limitations are”. Luckily, this tutorial covers all the critical context you need. Josh W Comeau 👀 If you're a bit more advanced, you might enjoy Alex MacArthur's look at controlling promises using Promise.withResolvers().

CHALLENGE

function* generator() {
  yield 1;
  yield new Promise(resolve => resolve(2));
  yield 3;
}

const gen = generator();
console.log(gen.next().value);
gen.next().value.then(console.log);
console.log(gen.next().value);

Even though Armenia 🇦🇲 is a small country, we have a really big JavaScript community 😎. There are many events related to JavaScript, and another one is happening tomorrow: JSConf Armenia 2024! If you are in Armenia and would like to attend, just grab your tickets from the website.

CHALLENGE

function* generator() {
  yield 1;
  yield 2;
  return 3;
}

const gen = generator();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);

🌲 Some updates related to the Node.js world

CHALLENGE

function* generator() {
  const value = yield 1;
  yield value;
}

const gen = generator();
console.log(gen.next().value);
console.log(gen.next(2).value);

🍊 Qlock: A JavaScript Quine Clock We linked to Martin's array of creative JavaScript experiments earlier, but why not finish with one that particularly tickled us? A quine is a program that takes no input but manages to produce, as output, its own source code. Here’s a fun JavaScript example that isn’t merely a quine, but a clock too. Martin Kleppe

CHALLENGE

function* generator1() {
  yield 1;
  yield 2;
}

function* generator2() {
  yield* generator1();
  yield 3;
}

const gen = generator2();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);

✌️ Regexper: Display JavaScript Regular Expressions as Railroad Diagrams Might come in handy for learning regular expressions or if you have a complex regular expression and you don’t know what it does (not an uncommon situation..!) Jeff Avallone

CHALLENGE

function* generator() {
  yield 1;
  yield* [2, 3];
  yield 4;
}

const gen = generator();
for (const value of gen) {
  console.log(value);
}