IT技术 - react挂钩陈旧状态 - 吾爱随笔录

我试图在回调中异步调用 setState，问题是当我的函数调用 setState 时，状态已被另一个发生的事件更新。有没有办法从嵌套回调中查询当前状态？

这是一个简单的演示，展示了我遇到的问题：

https://stackblitz.com/edit/react-uybyyn

import React, { Component, useState } from 'react';
import { render } from 'react-dom';

function App() {
  const [state, setState] = useState({value: 0});
  const click = async () => {

    setTimeout(() => setState({value: state.value + 10}), 300);

    async function apiCall(state) {
      // fake it for now
      return new Promise((res) => {
        setTimeout(() => {
          // !!!Get the latest state here!!!
          res({value: state.value + 1});
        }, 1000)
      });
    }

    const newState = await apiCall(state);
    setState(newState);
  }
  return (
    <div>
      Value: {state.value}
      <button onClick={click}>Update</button>
    </div>
  );
}

render(<App />, document.getElementById('root'));

const [val ,setVal] = React.useState(initVal); const obj = { str: 'Hello' }; // Merge state form — seVal(obj); // Function updater form — seVal(prevState => { // Object.assign would also work return {...prevState, ...{ str: prevState.str + ' World' }}; });