> For the complete documentation index, see [llms.txt](https://easonwang.gitbook.io/web_advance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://easonwang.gitbook.io/web_advance/html5/intersectionobserver.md).

# IntersectionObserver

可以用來偵測目前畫面是否捲動到特定元素，可用來作 infinite scroll 等功能。

```javascript
let options = {
  root: document.querySelector('#scrollArea'),
  rootMargin: '0px',
  threshold: 1.0
}

let observer = new IntersectionObserver(callback, options);
```

<https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API>