JavaScript Page_visibility Guide
Page Visibility API detects when a tab becomes visible or hidden for saving resources and pausing media. The guide walks through Visibility State. `document.visibilityState` — "visible" or "hidden". `document.addEventListener("visibilitychange",()=>{})` — listen. Use: pause video/audio when hidden, stop animations/ polling, save draft, update title. `document.hidden` — legacy boolean. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.