mathiasbynens/jquery-visibility

This jQuery plugin provides a simple API to execute callbacks when a page's visibility state changes, using the Page Visibility API where supported and falling back to focus/blur events in older browsers. It's designed for developers who want to easily pause/resume media, slideshows, or other content based on whether the page is visible to the user. The plugin offers custom 'show' and 'hide' events that can be used to detect when the page gains or loses visibility.