Do you know what will be the output of this code? console.log([NaN].indexOf(NaN), [NaN].includes(NaN));

Why does indexOf not find NaN but includes does?

Do you know what will be the output of this code?

JavaScript

console.log([NaN].indexOf(NaN), [NaN].includes(NaN));

Show answer and explanation

The answer is -1 true.

indexOf compares with ===, and NaN is never strictly equal to itself. includes uses the SameValueZero algorithm, which does match NaN.