<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<meta name="apple-mobile-web-app-capable" content="yes" />
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" />
<title></title>
<style>
#content {
width: 100vw;
height: 100vh;
}
#info {
position: fixed;
top: 0;
}
#target {
width: 100px;
height: 100px;
background: red;
}
</style>
</head>
<body>
<div id="info">我藏在页面底部，请向下滚动</div>
<div id="content"></div>
<div class="test">adsfasfd</div>
<div id="target"></div>
<div id="h" style="height:1000px;"></div>
<div class="test">adsfasfd</div>
</body>
<!-- -->
<script type="text/javascript">
function query(selector) {
return Array.from(document.querySelectorAll(selector));
}
let observer = new IntersectionObserver(function (entries) {
entries.forEach(function (element, index) {
// console.log(observer.takeRecords());
if (element.isIntersecting) {
info.textContent = "我出来了";
} else {
info.textContent = "我藏在页面底部，请向下滚动"
}
});
}, {
root: null,
threshold: [0, 1]
})
query(document.querySelectorAll(‘.test‘).forEach((item) => {
observer.observe(item);
}))
// observer.observe(document.querySelectorAll(‘.test‘)[0])
</script>
</html>
IntersectionObserver API js懒加载实现方法