Introduction to React Context API with Firebase Authentication

Hi Bhanu, thanks for the question.

According to official docs, useMemo will only recompute the memoized value when one of the dependencies has changed.

In this case, onAuthStateChanged() does the job of useMemo so there's no need to use it.

In general, it is useful for when you need to optimize performance by avoiding expensive computation functions.

const memoizedValue = useMemo(() => computeExpensiveValue(a, b), [a, b]);

I will write a more detailed article in the future. Thank you!