[Typo]: "A stopwatch" example for useRef does not cleanup correctly

[jacobgmathew]

Summary

In "A stopwatch" example for useRef an interval is set in handleStart(). It is cleared in handleStop(). But if the component is unmounted after the interval is started, but without stopping it, it is never cleared, which means setNow can get called on an unmounted component.

Page

https://react.dev/reference/react/useRef#examples-value

Details

No response

[sachanritik1]

adding this useEffect(() => { return () => handleStop() },[]) should do it.

I have opened a PR.