DOM VisibilityChange

gistfile1.js

var Sandvik = Sandvik || { Utils: {} };
Sandvik.Utils.VisibilityChange = (function() {
    function ctor(cb) {
        var self = this;
        this.visibilityState = true;
        var visProp = (function() {
            var prefixes = ['webkit', 'moz', 'ms', 'o'];
            if ('hidden' in document) return 'hidden';
            for (var i = 0; i < prefixes.length; i++) {
                if ((prefixes[i] + 'Hidden') in document)
                    return prefixes[i] + 'Hidden';
            }
            return null;
        })();
        if (visProp) {
            var evtname = visProp.replace(/[H|h]idden/, '') + 'visibilitychange';
 
            document.addEventListener(evtname, function(evt) {
                self.visibilityState = evt.target.visibilityState;
                cb(self.visibilityState, evt);
            });
        }
    }
    return ctor;
})();