In JavaScript, in what situation(s) is a === b, but using a or b can give different results?

Question

It may look like if a === b is true, then any operation using either a or b should give the exact same result.

But I do see an exception: 0 === -0 but 1/0 gives Infinity and 1/-0 gives -Infinity.

Are there any other case(s) in JavaScript this can happen?

Answer 1

No. According to the Strict Equality Comparison Algorithm (EcmaScript §11.9.6) this is the only exception where two different values produce true.

However, a similar pitfall exists for the reverse situation: NaN is an exception where calling the algorithm with the exact same value yields false.