Engine-Level Behaviour — Series 2

Preview — 3 of 10 questions

What is the output?

javascript

const obj = {};
obj.b = 1;
obj[2] = 'two';
obj.a = 3;
obj[1] = 'one';

console.log(Object.keys(obj));

A["a", "b", "1", "2"]

B["b", "2", "a", "1"]

C["1", "2", "b", "a"]

D["2", "1", "b", "a"]

What is the output?

javascript

const str = 'hello';
str.customProp = 'test';

console.log(str.customProp);
console.log(typeof str);

A"test", "string"

B"test", "object"

Cundefined, "object"

Dundefined, "string"

What is the output?

javascript

function factorial(n, acc = 1) {
  if (n <= 1) return acc;
  return factorial(n - 1, n * acc);
}

try {
  console.log(factorial(100000));
} catch (e) {
  console.log(e instanceof RangeError);
}

AThe full, correctly computed factorial of 100000 — a very large number.

Btrue

Cfalse

DInfinity

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