1 useState与useReducer
2 useEffect与useLayoutEffect
3 useMemo与useCallback
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4 React.memo
function memo(type,compare) {
const elementType = {
$$typeof: REACT_MEMO_TYPE,//核心是这个标记,在beginWork进入和普通functionComponent不同的处理逻辑
type,
compare: compare === undefined ? null : compare,
};
return elementType;
}