# 监听元素进去窗口和怎样利用localStorage 做本地过期缓存
# 本地过期缓存, 一天一次
export function shouldShowToday(uid: number): boolean {
const storageKey = `dailyShow_${uid}`;
const storedDateStr = localStorage.getItem(storageKey);
const todayDateStr = new Date().toISOString().split('T')[0]; // "YYYY-MM-DD"
if (!storedDateStr || storedDateStr !== todayDateStr) {
localStorage.setItem(storageKey, todayDateStr);
return true;
}
return false;
}
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# 监听页面元素是否出现在 视窗中
export function observeElementInViewport(
element: HTMLElement,
callback: (isIntersecting: boolean, entry: IntersectionObserverEntry) => void,
options: IntersectionObserverInit = {},
): () => void {
// 默认配置
const defaultOptions: IntersectionObserverInit = {
threshold: 0,
root: null,
rootMargin: '0px',
};
// 合并配置
const observerOptions: IntersectionObserverInit = {
...defaultOptions,
...options,
};
// 创建观察者实例
const observer = new IntersectionObserver(
(entries: IntersectionObserverEntry[]) => {
entries.forEach((entry) => {
callback(entry.isIntersecting, entry);
});
},
observerOptions,
);
// 开始观察元素
observer.observe(element);
// 返回取消观察的函数
return () => observer.unobserve(element);
}
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useLayoutEffect(() => {
if (showMask) {
const targetElement = document.querySelector('#learnMore') as HTMLElement;
// 定义回调函数
const handleVisibilityChange = (isVisible: boolean): void => {
if (isVisible) {
reportGIO('vip_guide_expose', {
from: '个人题库',
categoryId: CATEGORY_ID || '-1',
});
}
};
// 开始观察
const unobserve = observeElementInViewport(
targetElement,
handleVisibilityChange,
{
threshold: 0.5, // 当元素50%可见时触发回调
rootMargin: '0px 0px -100px 0px', // 底部缩小100px的视口范围
},
);
// 离开就不观察了
return unobserve;
}
}, [showMask]);
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