React 热键无法访问更新状态

Question

我正在使用react-hotkeys 库提供的GlobalHotKeys 在输入指定的键盘快捷键时触发某些事件。但是处理函数无法获取状态的更新值。以下是我使用的代码。

代码沙盒代码可在此处获得：this link

import React from 'react'
import { GlobalHotKeys } from 'react-hotkeys'

function Playground() {

  const [count, setCount] = React.useState(0)

  const handleEvent = React.useCallback(() => {
    console.log("Count Value now is: ", count)
  }, [])

  return (
    <GlobalHotKeys
      keyMap={{
        FOCUS_BARCODE: 'alt+a'
      }}
      handlers={{
        FOCUS_BARCODE: handleEvent
      }}>
      <div>
        <h1>Here is count value: {count}</h1>
        <button onClick={() => setCount((count) => count + 1)}> Increase Count</button>
      </div>
    </GlobalHotKeys>
  )
}

export default Playground

现在发生了什么

任何时候我点击alt+a，它的控制台日志都算作0。我点击了Increase count 按钮并增加了count 的值，然后点击alt+a 仍然将count 的值设为0。

我需要什么

我想用热键打印count 的更新值。

Answer 1

我已更新您的代码示例以使用热键。您必须将控制台日志放入 useEffect 调用中，因为这是副作用。

import React, { useEffect } from "react";
import { GlobalHotKeys } from "react-hotkeys";

function Playground() {
  const [count, setCount] = React.useState(0);

  const handleEvent = React.useCallback(() => {
    setCount((count) => count + 1);
  }, [setCount]);

  useEffect(() => {
    console.log("Count Value now is: ", count);
  }, [count]);

  return (
    <GlobalHotKeys
      keyMap={{
        FOCUS_BARCODE: "alt+a"
      }}
      handlers={{
        FOCUS_BARCODE: handleEvent
      }}
    >
      <div>
        <h1>Here is count value: {count}</h1>
        <button onClick={() => setCount((count) => count + 1)}>
          {" "}
          Increase Count
        </button>
      </div>
    </GlobalHotKeys>
  );
}

export default Playground;

沙盒 - https://codesandbox.io/s/laughing-newton-08vyv

useEffect - https://reactjs.org/docs/hooks-effect.html

Answer 2

你必须添加allowchanges..

<GlobalHotKeys
      keyMap={{
        FOCUS_BARCODE: 'alt+a'
      }}
      handlers={{
        FOCUS_BARCODE: handleEvent
      }} 
     allowChanges={true}
  >
      <div>
        <h1>Here is count value: {count}</h1>
        <button onClick={() => setCount((count) => count + 1)}> Increase Count</button>
      </div>
    </GlobalHotKeys>