在将数据发送或加载到本地存储时出现问题，当我刷新时，cart数据无法显示.我正在从firebase加载数据

Question

我正在从firebase加载数据，所以当我刷新时，加载它需要时间。添加的数据不在购物车中，这就是为什么我没有在购物车里获得任何产品的原因。但我确实遵循了相同的过程来存储用户数据，而且它运行良好，这意味着我在控制台中获得了一个注册的配置文件。有人能给我一个在购物车中获取数据的解决方案吗？

发送数据：

import { motion } from "framer-motion";
import React, { useEffect, useRef, useState } from "react";
import { MdShoppingBasket } from "react-icons/md";
import { actionType } from "../context/reducer";
import { useGlobalState } from "../context/stateProvider";
import NotFound from "../img/NotFound.svg";
const RowContainer = ({ flag, data, scrollValue }) => {
const [{ cartItems }, dispatch] = useGlobalState();
const [items, setItems] = useState([]);
const rowContainer = useRef();
const addToCart = () => {
dispatch({
type: actionType.SET_CARTITEMS,
cartItems: items,
});
localStorage.setItem("cartItems", JSON.stringify(items));
};
useEffect(() => {
addToCart();
}, [items]);
useEffect(() => {
rowContainer.current.scrollLeft += scrollValue;
}, [scrollValue]);
return (
<div
ref={rowContainer}
className={`w-full my-12 flex items-center ${
flag
? "overflow-x-scroll scrollbar-none scroll-smooth"
: "overflow-x-hidden flex-wrap justify-center"
}`}
>
{data && data.length > 0 ? (
data.map((item) => {
const { id, price, imageURL, calories, title } = item;
return (
<div
key={id}
className="w-350 min-w-[300px] md:min-w-[380px] md:my-10  backdrop-blur-lg mx-1 my-2 lg:mx-2  "
>
<div className="w-full flex flex-row items-center justify-between bg-white rounded-lg drop-shadow-lg py-2 px-4 hover:bg-whiteAlpha min-h-[150px]">
<motion.img
whileHover={{ scale: 1.2 }}
src={imageURL}
alt="img"
className="w-30 max-h-40 -mt-8 duration-100  drop-shadow-2xl"
/>
<div className="flex flex-col items-end justify-end gap-4">
<motion.div
whileTap={{ scale: 0.75 }}
className="w-8 h-8 rounded-md bg-orange-500 hover:bg-orange-600 "
onClick={() => setItems([...new Set(cartItems), item])}
>
<MdShoppingBasket className="text-white text-2xl m-1" />
</motion.div>
<div className=" w-full">
<p className="text-gray-800 md:text-lg text-base text-right">
{title}
</p>
<p className="text-sm text-gray-500 text-right">
<span className="text-orange-600">$</span> {price}
</p>
</div>
</div>
</div>
</div>
);
})
) : (
<div className="w-full flex flex-col items-center justify-center">
<img src={NotFound} className="h-340" alt="" />
<p className="text-center my-2 text-xl text-red-500">No data found</p>
</div>
)}
</div>
);
};
export default RowContainer;

提取数据

export const fetchCart = () => {
const cartInfo =
localStorage.getItem("cartItems") !== "undefined"
? JSON.parse(localStorage.getItem("cartItems"))
: localStorage.clear();
return cartInfo ? cartInfo : [];
};

Answer 1

您正在毫无理由地清除数据

localStorage.getItem("cartItems") !== "undefined"

应该是

localStorage.getItem("cartItems") !== undefined