CHALLENGE
const user = {
name: 'Alice',
age: 30
};
const handler = {
get(target, prop) {
if (prop in target) {
return target[prop];
}
return `Property '${prop}' doesn't exist`;
},
set(target, prop, value) {
if (prop === 'age' && typeof value !== 'number') {
console.log('Age must be a number');
return false;
}
target[prop] = value;
return true;
}
};
const proxy = new Proxy(user, handler);
proxy.age = '32';
proxy.age = 32;
console.log(proxy.job);
π7β€3
What is the output?
Anonymous Quiz
20%
undefined
45%
Age must be a number Property 'job' doesn't exist
19%
Age must be a number
16%
Property 'job' doesn't exist
π3β€2π₯2
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π€£45π12β€2π₯1π€1
CHALLENGE
function executePromises() {
console.log(1);
setTimeout(() => {
console.log(2);
}, 0);
Promise.resolve().then(() => {
console.log(3);
setTimeout(() => {
console.log(4);
}, 0);
}).then(() => {
console.log(5);
});
console.log(6);
}
executePromises();
β€3π₯3π1
What is the output?
Anonymous Quiz
23%
1, 6, 3, 2, 5, 4
25%
1, 6, 2, 3, 5, 4
24%
1, 3, 5, 6, 2, 4
28%
1, 6, 3, 5, 2, 4
π6π€©5β€2π₯1
Several years in the making, the record and tuples proposal offered two new deeply immutable data structures to JavaScript, but at this weekβs TC39 meeting, the consensus was to drop it.
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π7π€4π€£3β€2π₯1
CHALLENGE
function main() {
console.log(1);
setTimeout(() => console.log(2), 0);
Promise.resolve().then(() => {
console.log(3);
setTimeout(() => console.log(4), 0);
}).then(() => console.log(5));
Promise.resolve().then(() => console.log(6));
console.log(7);
}
main();
β€5π2
What is the output?
Anonymous Quiz
25%
1, 3, 5, 6, 7, 2, 4
37%
1, 7, 3, 6, 5, 2, 4
16%
1, 7, 6, 3, 5, 2, 4
22%
1, 7, 3, 5, 6, 2, 4
π6π₯3β€2
Even if you donβt want to render a neat plasma-style effect on the Web, this is a wonderfully deep exploration of the math and technology behind doing so using simple GLSL code that could be easily understood by any JavaScript developer.
Alex Harri
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β€3π2π€£2
CHALLENGE
const team = {
members: ['Alice', 'Bob', 'Charlie'],
[Symbol.iterator]: function*() {
let index = 0;
while(index < this.members.length) {
yield this.members[index++].toUpperCase();
}
}
};
const result = [];
for (const member of team) {
result.push(member);
}
console.log(result.join('-'));
π4
What is the output?
Anonymous Quiz
30%
Alice-Bob-Charlie
19%
TypeError: team is not iterable
47%
ALICE-BOB-CHARLIE
5%
[object Object]
π9β€2π₯2