document.visibilityState: Values representing the following 4 possible states: hidden: the page is in the background tab or the browser is minimized visible: the page is in the foreground tab prerender: the page performs pre-rendering processing off the screen document. The value of hidden is true unloaded: The page is being unloaded from memory Visibilitychange event: This event is triggered when the document changes from visible to invisible or from invisible to visible.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
You can use onbeforeunload and onunload
You can use HTML5’s Page Visibility API
document.visibilityState: Values representing the following 4 possible states:
hidden: the page is in the background tab or the browser is minimized
visible: the page is in the foreground tab
prerender: the page performs pre-rendering processing off the screen document. The value of hidden is true
unloaded: The page is being unloaded from memory
Visibilitychange event: This event is triggered when the document changes from visible to invisible or from invisible to visible.