小编nik*_*sqy的帖子

为什么 useSelector 里面的选择器会运行两次？

例子

const selector = (state) => {
  console.log("invoke Selector");

  return state;
};

function App() {
  console.log("render App");

  const count = useSelector(selector);
  const dispatch = useDispatch();
  return (
    <div className="App">
      <button onClick={() => dispatch({ type: "INCREMENT" })}>Increment</button>
      <button onClick={() => dispatch({ type: "DECREMENT" })}>Decrement</button>
      <p>{count}</p>
    </div>
  );
}

这是一个工作片段，显示每次 Child 安装时选择器回调运行两次：

const selector = (state) => {
  console.log("invoke Selector");

  return state;
};

function App() {
  console.log("render App");

  const count = useSelector(selector);
  const dispatch = useDispatch();
  return (
    <div …