Creating Well-Behaved Sites With The Page Visibility API
https://www.smashingmagazine.com/2015/01/creating-sites-with-the-page-visibility-api/
WEBJan 20, 2015 · The Page Visibility API spec is surprisingly simple, consisting of just two methods: document.hidden returns true or false depending on the status of the browser window; and those same states are reflected in string form for document.visibilityState (hidden and visible, respectively, with two optional values of prerender and unloaded), …
DA: 16 PA: 36 MOZ Rank: 79