Channel: JavaScript
What is the output?
Anonymous Quiz
26%
BANANA-CHERRY-DATE
45%
BAN-CHE
21%
BANANA-CHERRY
8%
BAN-CHE-DAT
π₯9π€2β€1
Hono is a framework well worth exploring. Itβs fast, lightweight, built on Web Standards, and can be used to build apps that work on numerous platforms from Node or Bun to Cloudflare or Fastly. v4.8 adds new route helper functions, improvements to JSX streaming and CORS, a new plugin system for static site generation, and more.
Yusuke Wada and Contributors
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β€7π1π₯1
CHALLENGE
const numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const result = numbers
.filter(n => n % 2 === 0)
.map(n => n * 2)
.reduce((acc, curr, idx, arr) => {
if (idx === arr.length - 1) {
return (acc + curr) / arr.length;
}
return acc + curr;
}, 0);
console.log(result);
π₯2π€2β€1
π€8π€£3β€2
CHALLENGE
const teams = [
{ name: 'Warriors', players: ['Curry', 'Thompson'] },
{ name: 'Lakers', players: ['James', 'Davis'] }
];
const newTeams = JSON.parse(JSON.stringify(teams));
newTeams[0].players.push('Green');
const shallowCopy = [...teams];
shallowCopy[1].name = 'Clippers';
const freezeTest = Object.freeze({nested: {value: 42}});
freezeTest.nested.value = 100;
console.log(teams[1].name, teams[0].players.length, freezeTest.nested.value);
β€6π€£3
What is the output?
Anonymous Quiz
44%
Clippers 2 100
25%
Lakers 2 100
21%
Lakers 3 42
11%
Clippers 3 100
β€3π3π₯3
CHALLENGE
let x = 5;
function foo() {
console.log(x);
let x = 10;
console.log(x);
}
foo();
β€1
What is the output?
Anonymous Quiz
25%
ReferenceError: Cannot access 'x' before initialization
24%
undefined 10
14%
5 ReferenceError: x is not defined
36%
5 10
β€8π4π€£3π₯2
Deno 2.4 reintroduces the deno bundle command for creating single-file bundles for both the server and client side, complete with support for npm and JSR dependencies and automatic tree-shaking. You can also now include arbitrary files into modules using import, and Denoβs built-in OpenTelemetry support is now stable. Itβs a substantial release.
IwaΕczuk and Jiang
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β€3π2π₯1
CHALLENGE
const fruits = ['apple', 'banana', 'cherry'];
const newFruits = [...fruits];
newFruits.push('date');
const user = { name: 'Taylor', age: 30 };
const updatedUser = { ...user, age: 31 };
user.city = 'Seattle';
console.log(fruits.length, newFruits.length, user.city, updatedUser.city);
β€2
What is the output?
Anonymous Quiz
20%
3 4 undefined undefined
22%
3 3 Seattle undefined
46%
3 4 Seattle undefined
12%
4 4 Seattle Seattle
CHALLENGE
const handler = {
get(target, prop) {
if (prop in target) {
return target[prop] * 2;
} else {
return `Property ${prop} not found`;
}
},
set(target, prop, value) {
if (typeof value === 'number') {
target[prop] = Math.round(value);
return true;
}
return false;
}
};
const obj = { a: 5, b: 10 };
const proxy = new Proxy(obj, handler);
proxy.c = 7.8;
proxy.d = "hello";
console.log(obj.c, proxy.a, proxy.x);β€1
What is the output?
Anonymous Quiz
31%
8 10 "Property x not found"
24%
8 10 undefined
29%
8 10 Property x not found
16%
7.8 10 Property x not found
π€5β€3π1
A straightforward, practical look at bringing together several technologies and skills to create an AI powered color suggestion tool (which you can try here β results may vary, as seen above). The techniques covered can be used for many different practical ends.
LΓΊΓ Smyth
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π₯5β€2π2
CHALLENGE
const map = new WeakMap();
let obj1 = { name: 'user1' };
let obj2 = { name: 'user2' };
map.set(obj1, 'data for user1');
map.set(obj2, 'data for user2');
console.log(map.has(obj1));
obj1 = null;
// After garbage collection runs
console.log(map.has(obj1));
console.log(map.get(obj2));
What is the output?
Anonymous Quiz
22%
true ReferenceError: obj1 is not defined
43%
true false data for user2
16%
true false undefined
19%
true false 'data for user2'
β€3π1π₯1
A WYSIWYG Markdown editor framework based around a plugin system that enables a significant level of customization. The docs are rendered by Milkdown itself and thereβs a neat βplaygroundβ experience to try as well. GitHub repo.
Mirone
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β€2π2π₯1
CHALLENGE
function createCounter() {
let count = 0;
function increment() {
count++;
return count;
}
function decrement() {
count--;
return count;
}
return { increment, decrement, reset: () => count = 0 };
}
const counter = createCounter();
counter.increment();
counter.increment();
counter.decrement();
const { increment, reset } = counter;
increment();
reset();
increment();
console.log(counter.increment());π₯4β€2π1
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π€£25π5β€3π₯2
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