How to write a debounce service in AngularJS

Question

The underscore library provides a debounce function that prevents multiple calls to a function within a set period of time. Their version makes use of setTimeout.

H

Answer 1

Pete BD gave a good start to the debounce service, however, I see two problems:

1. returns when you should send in a work() callback that uses javascript closure if you need to change state in the caller.
2. timeout variable - isn't that timeout variable a problem? timeout[] maybe? imagine 2 directives using debounce - signalr, input form validator, I believe the factory approach would break down.

What I am currently using:

I changed factory to a service so each directive gets a NEW instance of debounce aka new instance of the timeout variable. - i haven't ran into a situation where 1 directive will need timeout to be timeout[].

.service('reactService', ['$timeout', '$q', function ($timeout, $q) {
    this.Debounce = function () {
        var timeout;

        this.Invoke = function (func, wait, immediate) {
            var context = this, args = arguments;
            var later = function () {
                timeout = null;
                if (!immediate) {
                    func.apply(context, args);
                }
            };
            var callNow = immediate && !timeout;
            if (timeout) {
                $timeout.cancel(timeout);
            }
            timeout = $timeout(later, wait);
            if (callNow) {
                func.apply(context, args);
            }
        };
        return this;
    }
}]);

in my angularjs remote validator

    .directive('remoteValidator', ['$http', 'reactService', function ($http, reactService) {
        return {
            require: 'ngModel',
            link: function (scope, elm, attrs, ctrl) {
                var newDebounce = new reactService.Debounce();

                var work = function(){
//....
                };

                elm.on('blur keyup change', function () {
                   newDebounce.Invoke(function(){ scope.$apply(work); }, 1000, false);
                });
            }
        };
    }])