QuestenaPractice that shows what to review next
SearchCreate a test
Question 53

What does [NaN].includes(NaN) return?

  1. -1
  2. undefined
  3. false
  4. trueCorrect answer

Explanation

Array includes uses SameValueZero comparison, under which NaN matches NaN, so the result is true. Assuming the strict-equality NaN rule here applies the wrong comparison semantics to this method.

Continue with this test

Start practice
Understand this topic (≈6 min)Back to test
Question 53: What does [NaN].includes(NaN) return? · JavaScript Fundamentals · Questena