TimerRefresher.js

// Runs tasks periodically. Is able to freeze when page is not active.
// Requires visibility.js: https://github.com/ai/visibilityjs

angular.module('someting', [])


.run(['$rootScope', function($rootScope) {

  // wrapping visibility API into $rootScope.
  // page becomes hidden when user switched tabs or minimized the window
  $rootScope.pageHidden = function() {
    return Visibility.isSupported() && Visibility.hidden();
  }

  // broadcasts when visibility changes and returns true/false as message
  // true - visible, false - invisible
  Visibility.change(function (e, state) {
    $rootScope.$broadcast('pageVisibilityChanged', state !== 'hidden');
  });

}])


.factory('TimerRefresher', ['$rootScope', '$timeout',
  function($rootScope, $timeout) {

  var TimerRefresher = function(defaultTimeout, defaultHandler) {
    this.defaultTimeout = defaultTimeout || 5;
    this.defaultHandler = defaultHandler;

    var self = this;
    // monitor page visibility changes.
    // if page is invisible, background tasks that connect to the server
    // stop to take load off it.
    // if page becomes visible, the tasks are started again.
    $rootScope.$on('pageVisibilityChanged', function(becameVisible) {
      self.pause()
      if (becameVisible) self.resume();
    });
  }

  TimerRefresher.prototype.start = function() {
    if (!this.started) {
      this.started = true;
      this.resume();
    }
  }
  TimerRefresher.prototype.stop = function() {
    this.pause(); this.started = false;
  }
  TimerRefresher.prototype.pause = function() { $timeout.cancel(this.timer); }
  TimerRefresher.prototype.resume = function() {
    if (!this.started) return;
    if ($rootScope.pageHidden()) return;

    return this.onTimeOut();
  }
  TimerRefresher.prototype.restart = function() {
    this.stop(); this.start();
  }

  TimerRefresher.prototype.onTimeOut = function() {
    // do something...
    if (this.defaultHandler) this.defaultHandler();

    // and then schedule next run
    this.schedule();
  }

  TimerRefresher.prototype.schedule = function(seconds) {
    var self = this;
    this.timer = $timeout(function() { self.resume(); }, (seconds || this.defaultTimeout) * 1000);
  }

  return TimerRefresher;
}])