javascript - How does JS listen to the focus gaining and losing focus events of the browser page window?

Question

For example:

当切换其他页面，当前页面失去焦点时，当前页面所执行的脚本停止，切换回来之后继续之前的脚本开始执行。

Answer 1

Try visibilitychange event

Answer 2

window.onfocus and window.onblur also work