Throttle and Debounce for AngularJS

services.js

	/**
	 * Throttling callbacks with specified delay.
	 * inspired by @link http://benalman.com/projects/jquery-throttle-debounce-plugin/
	 *
	 * Throttle is invoking callback for the first time and after that every delay.
	 * Debounce IS NOT invoking callback for the first time.
	 */
	angular.forEach(['Throttle', 'Debounce'], function (factoryName) {

	module
		.factory(factoryName, ['$rootScope', function ($rootScope)
		{
			var allTimeouts = {};
			$rootScope.$on('$routeChangeStart', function() {
				for (var i in allTimeouts) {
					clearTimeout(allTimeouts[i]);
				}
				allTimeouts = {};
			});

			/**
			 *
			 * @param {Number} delay in ms
			 * @param {Boolean} noTrailing it is to prevent execution one last time after all invokation stopped
			 * @param {Object} $scope
			 * @param {Function} callback
			 * @returns {Function} this function will be invoked each time
			 */
			return function (delay, noTrailing, $scope, callback) {
				var unique = Math.round(Math.random() * 1e15),
					timeoutId,
					lastExec = factoryName === 'Debounce' ? (+new Date) : 0;

				if (typeof noTrailing != 'boolean')
				{
					callback = $scope;
					$scope = noTrailing;
					noTrailing = undefined;
				}

				// this wrapper will be invoked by consumers
				function wrapper()
				{

					var me = this,
						elapsed = factoryName === 'Debounce' ? 0 : ((+new Date) - lastExec),
						args = arguments;

					timeoutId && clearTimer();

					if (elapsed > delay) {
						exec();
					}
					else if (! noTrailing)
					{
						timeoutId = setTimeout(function () {exec()}, delay - elapsed);
						storeTimer();
					}

					// Executing given function
					function exec()
					{
						lastExec = +new Date;
						clearTimer();
						callback.apply(me, args);
						if (! $scope.$$phase) {
							$scope.$digest();
						}
					}

					function storeTimer()
					{
						allTimeouts[unique] = timeoutId;
					}
					function clearTimer()
					{
						clearTimeout(timeoutId);
						allTimeouts[unique] = timeoutId;
					}
				}

				return wrapper;
			};
		}]);
	});