Are you ready for this?

Ten questions, free, marked as you go, written at exactly the level of the DSA for Frontend Certification. Nothing is recorded and no account is needed — it exists so you can decide for yourself rather than take our word for it.

The real paper is 50 questions in one sitting with a 70% pass mark and no partial credit. It is not a certificate of attendance, and roughly a third of it is foundations — the point is the whole language, not the parts you enjoyed.

Question 1 of 10

Big-O reasoning for frontend code

What is the time complexity of processAll, and what's the specific reason it's worse than it looks?

function hasDuplicate(list, value) {
  return list.includes(value);
}

function processAll(items) {
  return items.filter((item) => hasDuplicate(items, item.id));
}

Pick an answer to see whether it is right. You cannot change it afterwards — that is the point.