Question

cart.js

const Cart = () => {
const cartListing = useSelector(state => state.cartList);
const {cart, loading, error} = cartListing;
const dispatch = useDispatch();
const removeFromCartHandler = (id) => {
    dispatch(removeFromCart(id))
};  // =======>>>>> This function needs to dispatch on onclick event but it fire on first time load and does not fire on click
useEffect(() => {
    dispatch(cartList());
    return () => {

    }       
},[]);
return(
<button type="button" className="button" onClick={removeFromCartHandler()} >Delete </button>

action.js

const cartList = () => async (dispatch) => {
  try {
    dispatch({ type: CART_LIST_REQUEST });
    const { data } = await axios.get('http://localhost:3001/cart');
    dispatch({ type: CART_LIST_SUCCESS, payload: data.data.cartRecords });
  }
  catch (error) {
    dispatch({ type: CART_LIST_FAIL, payload: error.message });
  }
};

const removeFromCart = (id) => async (dispatch) => {
 try {
    dispatch({ type: CART_REMOVE_ITEM, payload: id });
    const { data } = await axios.delete(`http://localhost:3001/cart/${id}`);
    dispatch({ type: CART_REMOVE_SUCCESS, payload: data });
 }
 catch (error) {
    dispatch({type: CART_REMOVE_FAIL, payload: error.message})
 }
};

export { cartList, removeFromCart };

我不知道为什么removeFromCartHandler（）在第一次加载时触发，而不是在单击时触发。我希望removeFromCartHandler（）这个函数在onclick事件上触发，而不是在第一次加载时触发，因为我也没有在useEffect钩cartList中添加第一次就很好的调度，但是removeFromCartHandler（）函数需要在onClick事件上调度。我想我在这里缺少钩子的概念。我是React-redux的新手，并停留在这里。任何帮助都会被申请

Answer 1

您的onClick处理程序错误。这样做

public static int getNumberOfYears(double targetBalance) {
    int years = 1;
    double balance = 10000;
    while (balance <= targetBalance) {
        balance *= 1.05;
        years++;
    }
    return years;
}

Answer 2

之所以调用它，是因为您正在调用它-将()放在removeFromCartHandler调用函数之后。

onClick={removeFromCartHandler()}

Answer 3

您需要添加更多代码以获得更好的上下文，但是您要做的就是这样

onClick={(e) => removeFromCartHandler(e, item.id)}

您的主函数希望获取ID，您必须以某种方式传递它。我假设您渲染购物车商品或执行类似操作，无论如何，此实现都不会传递正确的ID。

事件在on-redux中的onclick上触发

3 个答案: