react 使用HOOK函數在react-redux

1.和connet一樣，使用provider包裹整個項目

const store = createStore(rootReducer)

ReactDOM.render(
  <Provider store={store}>
    <App />
  </Provider>,
  document.getElementById('root')
)

2.useSelect 幫助我們獲取store的數據

const num = useSelector(state => state.num);

3.useDispatch() 分發數據

const dispatch = useDispatch()

import React from "react";
import { createStore } from "redux";
import { Provider, useSelector, useDispatch } from "react-redux";

const initialState = { num: 0 };

const reducer = (state, action) => {
  switch (action.type) {
    case "decrement":
      return { ...state, num: state.num - 1 };
    case "increment":
      return { ...state, num: state.num + 1 };
    default:

      return state;
  }
};

const store = createStore(reducer, initialState);

const ComponentUseReactRedux = () => {
  return (
    <div>
      <h2>ComponentUseReactRedux</h2>
      <Provider store={store}>
        <ChildComponentUseReactRedux />
      </Provider>
    </div>
  )
}

const ChildComponentUseReactRedux = () => {
  const num = useSelector(state => state.num);
  const dispatch = useDispatch();
  return (
    <div>
      <h3>Using useSelector, useDispatch</h3>
      Number: {num}
      <button onClick={() => dispatch({ type: "increment" })}>+</button>
      <button onClick={() => dispatch({ type: "decrement" })}>-</button>
    </div>
  );
};