A little browserify-able shim/wrapper for the Page Visibility API
npm install visibilityA little browserify-able shim/wrapper for the
Page Visibility API.

Creates a new EventEmitter that fires specific events when the pages's
visibility status has changed.
Returns true if the browser window is not currently visible. If the browser does not support the Page Visibility API, this method will always returnfalse.
Returns true if the browser window is currently visible. If the browser does not support the Page Visibility API, this method will always return true.
Called whenever the page's visibility is toggled, passing visible as a
boolean.
Called only when the page becomes visible again.
Called only when the page is hidden.
MIT. See LICENSE.md for details.