What is the output?
Anonymous Quiz
16%
1 2 done
56%
2 4 done
18%
undefined undefined done
10%
[object Object] [object Object] done
❤4👍1🔥1
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❤2👍1🔥1
CHALLENGE
const a = 9007199254740991n;
const b = BigInt(9007199254740991);
const c = 9007199254740992;
const d = BigInt(9007199254740992);
console.log(a === b);
console.log(Number(a) === c);
console.log(c === Number.MAX_SAFE_INTEGER + 1);
console.log(d > a);
console.log(typeof (a + 1n));
console.log(Number(d) === c);
What is the output?
Anonymous Quiz
22%
true true true true bigint true
42%
true false true true bigint true
29%
false true true false number true
8%
true true false true bigint false
❤3
CHALLENGE
const userInput = "<script>alert('xss')</script>";
const sanitized = userInput
.replace(/</g, '<')
.replace(/>/g, '>')
.replace(/"/g, '"')
.replace(/'/g, ''');
const credentials = {
username: 'admin',
password: 'secret123'
};
const safeLog = (obj) => {
const { password, ...safe } = obj;
return JSON.stringify(safe);
};
console.log(sanitized);
console.log(safeLog(credentials));CHALLENGE
const wm = new WeakMap();
const obj1 = {};
const obj2 = {};
const obj3 = obj1;
wm.set(obj1, 'first');
wm.set(obj2, 'second');
wm.set(obj3, 'third');
console.log(wm.get(obj1));
console.log(wm.get(obj2));
console.log(wm.get(obj3));
console.log(wm.has(obj1));
console.log(wm.size);
What is the output?
Anonymous Quiz
30%
third second third true undefined
25%
third second first true 2
35%
first second third true 3
10%
first second first false undefined
🔥3❤2👍1
CHALLENGE
const data = '{"name": "Maria", "age": 25, "skills": ["JavaScript", "Python"]}';
try {
const parsed = JSON.parse(data);
const modified = {
...parsed,
age: parsed.age + 5,
skills: [...parsed.skills, "TypeScript"]
};
const serialized = JSON.stringify(modified, null, 0);
const reparsed = JSON.parse(serialized);
console.log(reparsed.skills.length);
console.log(typeof reparsed.age);
} catch (error) {
console.log('Parse error');
}❤6
👍3🔥2🤔2❤1
CHALLENGE
const numbers = [1, 2, 3, 4, 5];
const pipeline = (...fns) => (value) => fns.reduce((acc, fn) => fn(acc), value);
const multiply = (x) => (y) => x * y;
const add = (x) => (y) => x + y;
const square = (x) => x * x;
const transform = pipeline(
multiply(2),
add(3),
square
);
const result = numbers.map(transform);
console.log(result);
👍6❤3
What is the output?
Anonymous Quiz
25%
[4, 16, 36, 64, 100]
51%
[25, 49, 81, 121, 169]
18%
[16, 36, 64, 100, 144]
5%
[9, 25, 49, 81, 121]
👍2❤1
The latest cutting edge version of Node has arrived with Web Storage enabled by default, JSON.stringify perf improvements, a new --allow-net option in the permission model, built-in Uint8Array base64/hex conversion, and WebAssembly and JIT optimizations. As shown in the diagram above, this means Node 24 will soon be promoted to being the 'active' LTS release and Node 22 will enter its 'maintenance' LTS phase.
Rafael Gonzaga
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CHALLENGE
function Vehicle(type) {
this.type = type;
}
Vehicle.prototype.describe = function() {
return `This is a ${this.type}`;
};
function Car(brand) {
Vehicle.call(this, 'car');
this.brand = brand;
}
Car.prototype = Object.create(Vehicle.prototype);
Car.prototype.constructor = Car;
Car.prototype.describe = function() {
return Vehicle.prototype.describe.call(this) + ` made by ${this.brand}`;
};
const tesla = new Car('Tesla');
console.log(tesla.describe());
console.log(tesla.constructor.name);❤1
What is the output?
Anonymous Quiz
26%
This is a Tesla made by Tesla Car
44%
This is a car made by Tesla Car
15%
This is a Tesla Vehicle
15%
This is a car made by Tesla Vehicle
1❤2👍1🔥1