A minor release whose headline feature is the (experimental) implementation of package maps (which let Node resolve packages from a static JSON file rather than walking node_modules). Matteo Collinaβs node:vfs subsystem also begins to make an appearance.
Antoine du Hamel
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π5β€3π₯1
CHALLENGE
class Pipeline {
#value;
#steps = [];
constructor(value) {
this.#value = value;
}
map(fn) {
this.#steps.push({ type: 'map', fn });
return this;
}
filter(fn) {
this.#steps.push({ type: 'filter', fn });
return this;
}
execute() {
return this.#steps.reduce((acc, step) => {
if (step.type === 'map') return acc.map(step.fn);
if (step.type === 'filter') return acc.filter(step.fn);
return acc;
}, this.#value);
}
}
const result = new Pipeline([1, 2, 3, 4, 5, 6])
.filter(x => x % 2 === 0)
.map(x => x ** 2)
.filter(x => x > 10)
.map(x => x - 1)
.execute();
console.log(result);π4β€1π₯1
β€1π₯1
A new framework from Vercel that provides Next.js-esque structure for building AI-powered agents using TypeScript and Markdown. It's quite Vercel-flavored by default, but I found you can run it entirely independently of Vercel with a few settings tweaks and your own keys. Project homepage.
Vercel
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β€3π₯2
CHALLENGE
console.log('start');
setTimeout(() => console.log('timeout 1'), 0);
Promise.resolve()
.then(() => {
console.log('promise 1');
setTimeout(() => console.log('timeout 2'), 0);
})
.then(() => console.log('promise 2'));
setTimeout(() => console.log('timeout 3'), 0);
queueMicrotask(() => console.log('microtask'));
console.log('end');β€4π₯3π2
What is the output?
Anonymous Quiz
30%
start end promise 1 microtask promise 2 timeout 1 timeout 3 timeout 2
38%
start end promise 1 promise 2 microtask timeout 1 timeout 3 timeout 2
21%
start end microtask promise 1 promise 2 timeout 1 timeout 2 timeout 3
11%
start end timeout 1 timeout 3 promise 1 microtask promise 2 timeout 2
β€4π₯1
CHALLENGE
const curry = (fn) => {
const arity = fn.length;
return function curried(...args) {
if (args.length >= arity) {
return fn(...args);
}
return (...moreArgs) => curried(...args, ...moreArgs);
};
};
const volume = (l, w, h) => l * w * h;
const curriedVolume = curry(volume);
const withLength5 = curriedVolume(5);
const withLength5Width3 = withLength5(3);
console.log(typeof withLength5);
console.log(typeof withLength5Width3);
console.log(withLength5Width3(2));
console.log(curriedVolume(5)(3)(2) === withLength5(3)(2));
β€3π₯3π1
What is the output?
Anonymous Quiz
21%
function function 30 false
27%
object function 30 true
36%
function function 30 true
17%
function number 30 true
π₯2β€1
CHALLENGE
const obj = {
name: "Quantum",
regular: function () {
return this.name;
},
arrow: () => {
return this?.name;
},
nested: function () {
const inner = () => this.name;
return inner();
},
};
console.log(obj.regular());
console.log(obj.arrow());
console.log(obj.nested());π4β€3π₯3
What is the output?
Anonymous Quiz
18%
undefined undefined Quantum
27%
Quantum Quantum Quantum
24%
Quantum undefined undefined
30%
Quantum undefined Quantum
π₯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 readOnly = userPermissions & ~flags.WRITE;
const toggled = userPermissions ^ flags.EXECUTE;
const shifted = (flags.DELETE << 2) | (flags.READ >> 0);
console.log(canDelete, readOnly, toggled, shifted);β€2π2π₯1
π€3β€1
CHALLENGE
function createUser(
name,
role = "viewer",
permissions = { read: true, write: false },
level = permissions.write ? 2 : 1
) {
return { name, role, permissions, level };
}
const user1 = createUser("Carlos");
const user2 = createUser("Diana", "editor", { read: true, write: true });
const user3 = createUser("Eve", "admin", undefined, 5);
console.log(user1.role, user1.level);
console.log(user2.role, user2.level);
console.log(user3.role, user3.level);
π₯5π€©2π1
What is the output?
Anonymous Quiz
16%
viewer 2 editor 2 admin 5
32%
viewer 1 editor 1 admin 5
39%
viewer 1 editor 2 admin 5
13%
viewer 1 editor 2 admin 2
β€3π1
CHALLENGE
const user = {
profile: {
name: "Marcus",
address: {
city: "Berlin",
zip: "10115"
}
},
getSubscription: () => ({
plan: "pro",
features: ["analytics", "exports"]
})
};
const city = user?.profile?.address?.city;
const country = user?.profile?.address?.country?.toUpperCase();
const firstFeature = user?.getSubscription?.()?.features?.[0];
const adminRole = user?.roles?.[0]?.name ?? "guest";
console.log(city, country, firstFeature, adminRole);π₯4π3π€©2β€1
What is the output?
Anonymous Quiz
20%
undefined undefined undefined guest
29%
Berlin null analytics null
44%
Berlin undefined analytics guest
8%
Berlin undefined undefined guest
π₯1
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π€£9π₯6π1π€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?.toUpperCase();
return result + transformed + str;
});
};
const name = "carlos";
const score = 42;
const bonus = null;
const output = tag`Player: ${name}, Score: ${score}, Bonus: ${bonus}`;
console.log(output);β€1
What is the output?
Anonymous Quiz
17%
Player: Carlos, Score: 84, Bonus: 0
29%
Player: carlos, Score: 42, Bonus: null
39%
Player: CARLOS, Score: 84, Bonus: undefined
16%
Player: CARLOS, Score: 84, Bonus: null
β€4π₯4π3