when i click add to favourites(adding on local storage but not updating count, when i click button ref, updating count我这样做是为了我的电子商务项目,我有愿望清单.当我添加项目到我的愿望清单,我添加项目到我的localStorage.我需要显示有多少项目我添加到我的愿望清单.我不知道如何呈现头(自动)当改变值(localStorage).
我添加了按钮,与onClick我打电话给cou.当我添加项目到愿望清单什么也没发生(不渲染)当我点击按钮一切都很好.有人可以帮助请?一切都在标题组件(页面)
const [count, setCount] = useState((JSON.parse(localStorage.getItem("liked"))));
const cou = () => {
let oldData = JSON.parse(localStorage.getItem('liked') || "[]")
if (oldData.length === count.length) {
setCount((JSON.parse(localStorage.getItem("liked"))))
} else {
setCount((JSON.parse(localStorage.getItem("liked"))))
}
};
useEffect(() => {
let oldData = JSON.parse(localStorage.getItem('liked') || "[]")
if (oldData.length === count.length) {
setCount((JSON.parse(localStorage.getItem("liked"))))
} else {
setCount((JSON.parse(localStorage.getItem("liked"))))
}
}, [(count.length)]);
表头上的此跨度
<span style={{ position: 'relative', left: '-21px', top: '-18px' }}>{count.length}</span>}
1条答案
按热度按时间gupuwyp21#
不要写
[(count.length)]
,你可以用[count]检查吗?请让我知道输出。