useeffect after component mount code example
Example 1: componentdidupdate in hooks
const App = props => {
const didMountRef = useRef(false)
useEffect(() => {
if (didMountRef.current) {
doStuff()
} else didMountRef.current = true
}
}
Example 2: clean up useeffect
useEffect(() => {
function handleStatusChange(status) {
setIsOnline(status.isOnline);
}
ChatAPI.subscribeToFriendStatus(props.friend.id, handleStatusChange);
return () => {
ChatAPI.unsubscribeFromFriendStatus(props.friend.id, handleStatusChange);
};
});