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

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CHALLENGE


const team = {
name: "Alpha",
members: ["Carlos", "Diana", "Eve"],

listMembers() {
return this.members.map(function (member) {
return `${this.name}: ${member}`;
});
},

listMembersArrow() {
return this.members.map((member) => {
return `${this.name}: ${member}`;
});
},
};

console.log(team.listMembers()[0]);
console.log(team.listMembersArrow()[0]);
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CHALLENGE

function makeCounter(start = 0, step = 1) {
let count = start;
const history = [];

return {
increment() {
count += step;
history.push(count);
return this;
},
decrement() {
count -= step;
history.push(count);
return this;
},
getHistory: () => history,
getCount: () => count,
};
}

const counter = makeCounter(10, 3);
counter.increment().increment().decrement();

console.log(counter.getCount());
console.log(counter.getHistory());
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CHALLENGE


const inventory = new Map([
["sword", { qty: 3, value: 150 }],
["shield", { qty: 1, value: 200 }],
["potion", { qty: 5, value: 30 }],
]);

const upgraded = new Map(
[...inventory.entries()]
.filter(([, item]) => item.value >= 100)
.map(([key, item]) => [key, { ...item, value: item.value * 2 }])
);

console.log(upgraded.size);
console.log(upgraded.get("sword").value);
console.log(upgraded.has("potion"));
console.log([...upgraded.keys()].join(", "));
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CHALLENGE

const log = [];

const handler = {
set(target, key, value) {
log.push(`set:${key}=${value}`);
target[key] = value;
return true;
},
get(target, key) {
log.push(`get:${key}`);
return target[key];
}
};

const state = new Proxy({}, handler);

state.count = 0;
state.count = state.count + 1;
state.count = state.count + 1;

console.log(log.join(" | "));
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Somewhere in Yerevan 🇦🇲😆
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CHALLENGE

const obj = {
name: "Nikola",
greetArrow: () => {
return `Hello, ${this?.name ?? "stranger"}!`;
},
greetRegular() {
return `Hello, ${this.name}!`;
},
greetNested() {
const inner = () => `Hi, ${this.name}!`;
return inner();
}
};

console.log(obj.greetArrow());
console.log(obj.greetRegular());
console.log(obj.greetNested());
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CHALLENGE

const a = 9007199254740991n;
const b = BigInt(Number.MAX_SAFE_INTEGER);

console.log(a === b);
console.log(a + 1n);
console.log(typeof a);
console.log(a === 9007199254740991);
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CHALLENGE


const config = {
timeout: 0,
retries: null,
host: "",
port: undefined,
debug: false,
};

const timeout = config.timeout ?? 3000;
const retries = config.retries ?? 5;
const host = config.host ?? "localhost";
const port = config.port ?? 8080;
const debug = config.debug ?? true;

console.log(timeout, retries, host, port, debug);
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👀 Hocuspocus 4: Add Real-Time Collaboration to Any App

A plug-and-play real-time collaboration backend based on Yjs so you can quickly and safely wire up multi-user collaborative experiences into a JavaScript app. It runs on Node, Bun, Deno, or Cloudflare Workers. GitHub repo.

Tiptap
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CHALLENGE

"use strict";

function createCounter() {
let count = 0;

return {
increment() { count++; },
get value() { return count; },
toString() { return `Counter: ${count}`; }
};
}

const counter = createCounter();
counter.increment();
counter.increment();
counter.increment();

try {
counter.value = 99;
} catch (e) {
console.log(`${e.constructor.name}: ${counter}`);
}
3
📊 Plotly 3.6: The Declarative Graphing Library

A long-standing library, also widely used in the Python and R ecosystems, that offers over 50 visualization types, from basic charts and graphs to maps, plots, and heatmaps.

Plotly, Inc.
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CHALLENGE


function Animal(name) {
this.name = name;
}

Animal.prototype.speak = function () {
return `${this.name} makes a sound.`;
};

function Dog(name, breed) {
Animal.call(this, name);
this.breed = breed;
}

Dog.prototype = Object.create(Animal.prototype);
Dog.prototype.constructor = Dog;

Dog.prototype.speak = function () {
return `${this.name} barks!`;
};

const dog = new Dog("Rex", "Labrador");

console.log(dog.speak());
console.log(dog instanceof Dog);
console.log(dog instanceof Animal);
console.log(Object.getPrototypeOf(dog) === Animal.prototype);
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