aleksnick

function TableContainer({ columns=[] }) {
    const [sizes, setSizes] = useState(getSizes(columns));
    
    const onAdd = useCallback((newcolumn) => {
      columns.push(newColumn);
    }, [columns]);
    
    useEffect(() => {
      setSizes(getSizes(columns));
    }, [columns]);

aleksnick

function TestComponent({ obj }) {
	if (!obj.someField) {
		return null;
	}

	const value = useSelector(customExpensiveSelector(obj.someField));

	return (
		<div>{value}</div>;
	);