CHALLENGE
const str = "JavaScript is Awesome!";
const result = str
.split(" ")
.map((word, i) =>
i % 2 === 0
? word.toUpperCase()
: word.toLowerCase()
)
.join("-");
const reversed = result
.split("")
.reduce((acc, char) => char + acc, "");
console.log(reversed);
π₯2β€1
What is the output?
Anonymous Quiz
39%
!EMOSEWA-si-TPIRCSAVAJ
24%
!emosewa-is-tpircsavaj
21%
!EMOSEWA-IS-TPIRCSAVAJ
15%
!emosewa-IS-tpircsavaj
β€4π₯2
Given a valid OpenAPI v3 or Swagger v2 spec, generate models, requests, hooks, and mocks for React, Vue, Svelte, Solid, and Hono apps, or even plain fetch.
Victor Bury
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β€4π2π₯1
CHALLENGE
const delay = (ms, val) => new Promise(res => setTimeout(res, ms, val));
async function* asyncGen() {
yield await delay(10, "alpha");
yield await delay(10, "beta");
yield await delay(10, "gamma");
}
async function run() {
const results = [];
const gen = asyncGen();
const [first, , third] = await Promise.all([
gen.next(),
gen.next(),
gen.next()
]);
results.push(first.value, third.value);
const p1 = Promise.resolve("x").then(v => v + "1");
const p2 = Promise.reject("err").catch(e => e + "2");
results.push(...(await Promise.all([p1, p2])));
console.log(results);
}
run();
β€7π3
What is the output?
Anonymous Quiz
19%
[ 'alpha', 'gamma', 'x1', 'err' ]
31%
[ 'alpha', 'beta', 'x1', 'err2' ]
26%
[ 'alpha', 'beta', 'x1', 'err' ]
25%
[ 'alpha', 'gamma', 'x1', 'err2' ]
β€2π₯1
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β€5π1π₯1
CHALLENGE
const tag = (strings, ...values) => {
return strings.reduce((result, str, i) => {
const value = values[i - 1];
const transformed =
typeof value === "number" ? `[${value ** 2}]` : `{${value}}`;
return result + transformed + str;
});
};
const name = "Sofia";
const score = 4;
const level = "gold";
const output = tag`Player: ${name}, Score: ${score}, Rank: ${level}`;
console.log(output);
π₯3β€2π2
For a while, Nodeβs long-standing web framework, Express.js, was looking a bit stale and projects like Fastify were beginning to carry the torch, but a major reboot that began in 2024 brought Express back to the fore. Now Expressβs brand, website, and docs have time-travelled to 2026 too.
Sebastian Beltran
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β€7π3π€©3
CHALLENGE
const prefix = "get";
const suffix = "Name";
const registry = {
[`${prefix}Full${suffix}`]: function () {
return `${this.first} ${this.last}`;
},
[`${prefix}Short${suffix}`]: function () {
return this.first[0] + ". " + this.last;
},
};
const person = {
first: "Leonardo",
last: "Fibonacci",
...registry,
};
const key = ["Full", "Short"][1];
console.log(person[`${prefix}${key}${suffix}`]());
β€1π1
What is the output?
Anonymous Quiz
36%
L. Fibonacci
28%
undefined
21%
Leonardo F.
16%
Leonardo Fibonacci
β€3π₯1
A codemod (used via npx codemod) that transforms code using Axios to leverage the WHATWG Fetch API, which is now natively available in Node.js. For some reason they donβt link to it in the post, but itβs here if you want to try it out (and hereβs the underlying code).
Augustin Mauroy
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β€5π3π€©1π€£1
CHALLENGE
const config = {
db: { host: "localhost", port: 5432 },
cache: { ttl: 300 },
};
Object.freeze(config);
config.debug = true;
config.db.port = 9999;
config.cache = { ttl: 600 };
const sealed = Object.seal({ version: "1.0", meta: { build: 42 } });
sealed.version = "2.0";
sealed.author = "devteam";
sealed.meta.build = 99;
console.log(
config.debug,
config.db.port,
config.cache.ttl,
sealed.version,
sealed.author,
sealed.meta.build
);
β€5
What is the output?
Anonymous Quiz
20%
undefined 9999 300 '1.0' undefined 42
41%
undefined 9999 300 2.0 undefined 99
27%
true 5432 300 '2.0' undefined 99
12%
undefined 5432 600 '1.0' 'devteam' 99
β€4π1
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π₯6π4β€2π€£2π€1
CHALLENGE
const flags = {
READ: 0b0001,
WRITE: 0b0010,
EXECUTE: 0b0100,
DELETE: 0b1000,
};
const userPermissions = flags.READ | flags.WRITE | flags.EXECUTE;
const adminPermissions = userPermissions | flags.DELETE;
const canDelete = (adminPermissions & flags.DELETE) !== 0;
const canExecute = (userPermissions & flags.EXECUTE) !== 0;
const readOnly = userPermissions ^ flags.WRITE;
console.log(canDelete, canExecute, readOnly, adminPermissions >> 1);
β€2π1π₯1
What is the output?
Anonymous Quiz
26%
true false 5 7
37%
false true 5 7
25%
true true 7 5
12%
true true 5 7
π4β€3
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]);
β€7π₯3π1
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());π3β€1