Function Component

import React from 'react'

const aaa = () => {
  return (
    <div>aaa</div>
  )
}

export default aaa

import React from 'react'

export const aaa = () => {
  return (
    <div>aaa</div>
  )
}

import React from 'react'

function aaa() {
  return (
    <div>aaa</div>
  )
}

export default aaa

import React from 'react'

export default function aaa() {
  return (
    <div>aaa</div>
  )
}

useState Hook

const [, set] = useState();

useEffect(() => {
    
    return cleanUp = () => {
        
    }
}, []);

const  = useContext();

const [state, dispatch] = useReducer(reducer, initialArg, init);

const  = useRef();

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

const memoizedCallback = useCallback(
    () => {
        doSomething(a, b)
    },
    [a, b],
);

const  = useSelector(state => state.);

const  = useDispatch();