CHALLENGE
try {
const arr = [1, 2, 3];
function processArray() {
try {
nonExistentFunction();
} catch (err) {
throw new TypeError('Invalid type');
}
}
try {
processArray();
} catch (err) {
console.log(err instanceof Error, err instanceof TypeError, err.message);
}
} catch (finalError) {
console.log('Caught in outer block:', finalError);
}
What is the output?
Anonymous Quiz
29%
true true Invalid type
38%
true false 'nonExistentFunction is not defined'
20%
true true 'Invalid type'
13%
false true 'Invalid type'
β€4π2π₯1
A library to use the power of ANSI escape sequences for coloring and styling text in many environments including the terminal, Chromium-based browsers, Node, Bun, Deno, and even Next.js. v4.0 is a big upgrade with enough breaking changes to warrant a migration guide for existing users.
webdiscus
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π5β€1π₯1
CHALLENGE
const target = { a: 1, b: 2 };
const handler = {
get(obj, prop) {
return prop in obj ? obj[prop] * 2 : 'Not found';
}
};
const proxy = new Proxy(target, handler);
// Add property to original object
target.c = 3;
// Modify existing property directly on proxy
proxy.a = 10;
// Use Reflect.get instead of direct property access
const result = Reflect.get(proxy, 'd', { custom: true });
console.log(proxy.a, proxy.b, proxy.c, result);
β€7π4π₯1
What is the output?
Anonymous Quiz
26%
10 4 6 Not found
28%
10 4 3 undefined
37%
20 4 6 Not found
8%
20 4 3 Not found
π3π₯2β€1
JavaScript (originally named LiveScript) turns thirty years old this year and the Deno team has put together a fantastic timeline-based tour of how much things have progressed from its first appearance in Netscape Navigator, through offshoots like JScript, standardization, and the introduction of Node.js, all the way through to the modern day.
The Deno Team
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β€12π2π₯1
CHALLENGE
function analyze(...items) {
const [first, ...rest] = items;
const { length } = [...rest, 'bonus'];
const result = {
...first,
count: length,
};
console.log(result);
}
analyze({ id: 42, name: 'Item' }, 'a', 'b');
What is the output?
Anonymous Quiz
20%
{ id: 42, count: 3 }
34%
{ id: 42, name: 'Item', count: 2 }
41%
{ id: 42, name: 'Item', count: 3 }
5%
{ count: 3 }
π₯4β€3π1
CHALLENGE
const user = { id: 1, name: 'Alice' };
const userData = new WeakMap();
userData.set(user, { lastLogin: '2023-01-01' });
const clone = { ...user };
const originalData = userData.get(user);
const cloneData = userData.get(clone);
console.log(originalData, cloneData);
β€1π1
Two members of the Angular team presented a session at this weekβs Google I/O event on the latest updates to the Angular framework in anticipation of the eventual release of Angular 20 next Thursday.
Chasanoff and Thompson (Google)
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π₯4π2
CHALLENGE
function mystery() {
try {
throw new Error('Oops');
return 'A';
} catch (err) {
return 'B';
} finally {
return 'C';
}
}
function wrapper() {
try {
return mystery();
} finally {
console.log('D');
}
}
console.log(wrapper());
π7
π₯3β€2π2
CHALLENGE
function compose(...funcs) {
return function(x) {
return funcs.reduceRight((acc, fn) => fn(acc), x);
};
}
const add10 = x => x + 10;
const multiply2 = x => x * 2;
const toString = x => `Result: ${x}`;
const composed = compose(toString, multiply2, add10);
console.log(composed(5));
π6β€1
π7π€4β€2π₯2
CHALLENGE
try {
try {
// Creating a custom error type
class CustomError extends Error {
constructor(message) {
super(message);
this.name = "CustomError";
}
}
const fn = () => {
throw new CustomError("Something went wrong");
};
try {
fn();
} catch (e) {
throw new TypeError("Type error occurred");
}
} catch (e) {
console.log(e instanceof Error, e.name, e instanceof TypeError);
}
} catch (e) {
console.log("Outer catch", e.message);
}
β€5π2π₯1
What is the output?
Anonymous Quiz
30%
true 'CustomError' false
32%
true 'TypeError' false
20%
false 'CustomError' false
18%
true 'TypeError' true
β€3π3π₯2
CHALLENGE
function* counter() {
let i = 1;
while (true) {
const reset = yield i++;
if (reset) {
i = 1;
}
}
}
const gen = counter();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next(true).value);
console.log(gen.next().value);
β€2
What is the output?
Anonymous Quiz
31%
1, 2, 1, 2
34%
1, 2, undefined, 1
20%
1, 2, 1, 1
14%
1, 2, 3, 4
π8β€2