Discussion on: Introduction to React.memo, useMemo and useCallback

[anh.nguyenvan]

Thanks for shared, it's very helpful, but i have a case, can you please help me clear
blog.axlight.com/posts/four-patter...

const App = props => {
const [stateA, dispatchA] = useReducer(reducerA, initialStateA);
const [stateB, dispatchB] = useReducer(reducerB, initialStateB);
const [stateC, dispatchC] = useReducer(reducerC, initialStateC);
const valueA = useMemo(() => [stateA, dispatchA], [stateA]);
const valueB = useMemo(() => [stateB, dispatchB], [stateB]);
const valueC = useMemo(() => [stateC, dispatchC], [stateC]);
return (



{props.children}



);
};
how the useMemo work? many thanks