visibility-broadcaster.js

(function () {
  'use strict';
  /** 
   * Broadcast changes to the page's visibility (via page visibility API)
   * Source: https://gist.github.com/sym3tri/9357439
   */
  function VisibilityService ($document, $rootScope, _) {
    var document = $document[0],
        features,
        detectedFeature;
 
    // Cross-browser implementation
    features = {
      standard: {
        eventName: 'visibilitychange',
        propertyName: 'hidden'
      },
      moz: {
        eventName: 'mozvisibilitychange',
        propertyName: 'mozHidden'
      },
      ms: {
        eventName: 'msvisibilitychange',
        propertyName: 'msHidden'
      },
      webkit: {
        eventName: 'webkitvisibilitychange',
        propertyName: 'webkitHidden'
      }
    };
   
    Object.keys(features).some(function(feature) {
      if (_.isBoolean(document[features[feature].propertyName])) {
        detectedFeature = features[feature];
        return true;
      }
    });
    
    // Feature doesn't exist in browser.
    if (!detectedFeature) {
      return;
    }

    $document.on(detectedFeature.eventName, broadcastChangeEvent);

    function broadcastChangeEvent () {
      $rootScope.$broadcast('visibilityChange', document[detectedFeature.propertyName]);
    }

    return {
      supported: !!detectedFeature
    }
  }

  angular.module('myServices').service('visibilityService', ['$document', '$rootScope', '_', VisibilityService]);
}).call(this);