关于react.js:react手写useState

let _state=[];
let index=0;
function myUseState(initialValue) {
  int currentIndex=index;    // 引入两头变量 currentIndex 就是为了保留以后操作的下标 index。_state[currentIndex] = _state[currentIndex]===undefined? initialValue:_state[currentIndex];
  const setState = (newValue) => {_state[currentIndex] = newValue; 
    render();};
  index+=1;// 每次更新完 state 值后，index 值 +1
  return [_state[currentIndex], setState];
}
const render = () => {
  index=0;    // 重要的一步，必须在渲染前后将 index 值重置为 0，不然 index 会一种减少 1
  ReactDOM.render(<App />, document.getElementById("root"));
};
// 应用 myUseState
const App = () => {const [n, setN] = myUseState(0);
  const [m, setM] = myUseState(0);
  return (
      <div classNam="App">
         <p>n:{n}</p>
         <button onClick={()=>{setN(n+1)}}>n+1</button> 
         <p>m:{m}</p>
         <button onClick={()=>{setM(m+1)}}>n+1</button> 
      </div>
      );
};
ReactDOM.render(<App />, document.getElementById("root"));