We can implement ArrayIncludes intrinsic by using ArrayIndexOf intrinsic.
No, we can share large part of ArrayIndexOf code. However, ArrayIncludes slightly different from ArrayIndexOf.
The includes method intentionally differs from the similar indexOf method in two ways. First, it uses the SameValueZero algorithm, instead of Strict Equality Comparison, allowing it to detect NaN array elements. Second, it does not skip missing array elements, instead treating them as undefined.