1. import React, { useState } from 'react';
    2. import ReactDOM from 'react-dom';
    3. // import useUpdate from './useUpdate.js';
    5. const rootElement = document.querySelector('#root');
    7. let _state = [];
    8. let _index = 0;
    10. const myUseState = (initialValue) => {
    11.   const currentIndex = _index;
    12.   _index += 1;
    13.   _state[currentIndex] = _state[currentIndex] || initialValue;
    14.   const setState = (newState) => {
    15.     _state[currentIndex] = newState;
    16.     render();
    17.   } 
    18.   return [_state[currentIndex], setState];
    19. }
    21. const render = () => {
    22.   _index = 0;
    23.   ReactDOM.render(<App />, rootElement);
    24. }
    26. const App = () => {
    27.   const [n, setN] = useState(0);
    28.   const [m, setM] = useState(0);
    29.   return (
    30.     <div>
    31.       n: {n} <button onClick={() => setN(n + 1)}>+1</button>
    32.       <hr />
    33.       m: {m} <button onClick={() => setM(m + 1)}>+1</button>
    34.     </div>
    35.   )
    36. }
    38. ReactDOM.render(<App />, rootElement);

    React Hooks