Call async function (or service) from within an AngularJs factory

Question

Call async function (or service) from within an AngularJs factory

I'm doing a iOS/Android app with Cordova and AngularJS and am new to all of this and have very basic JavaScript skills. The app is pretty basic, it just contains news items, events list (calendar) and other lists of information. The idea is that the app's contents will be updated from a web server and CMS, which will supply the app with JSON feeds.

This far, I have divided my content into several channels, NEWS, CALANDER, CONTACTS etc - each will have their own feed. I also have a master feed which indicates when each of the channels has been last updated at the server:

{
    "CALANDER":{"ITEM":"CALANDER","lastUpdate":"2014-10-30T17:12:59+00:00"},
    "CONTACTS":{"ITEM":"CONTACTS","lastUpdate":"2014-10-30T17:19:09+00:00"}
    "NEWS":{"ITEM":"NEWS","lastUpdate":"2014-10-30T16:25:08+00:00"}
}

So the idea is that the app will poll the server, every 5 min or so, and pull down just that small object.

In the app, I have a similar object stored (as a string) in local storage:

var masterFeedTimestamp = {
    "CALANDER":{"ITEM":"CALANDER","localTS":"2000-01-01T00:00:00.000Z"},
    "CONTACTS":{"ITEM":"CONTACTS","localTS":"2000-01-01T00:00:00.000Z"},
    "NEWS":{"ITEM":"NEWS","localTS":"2000-01-01T00:00:00.000Z"}
};

localStorage.setItem('masterFeedTimestamp',JSON.stringify(masterFeedTimestamp));

So when the JSON from the server is read, the timestamp for each channel is compared to what is in local storage and if there is newer content waiting on the server, go and get it.

The last bit is where I need help - what I would like to do is, from within the switch statement below, fire of a function/service/routine that will go and pull the news for example and update the news object in local storage. Ideally I'd like some sort of fire and forget system that would allow several updates to be queued. I don't think I need to worry about a return value - just have it update the content. In my code below I'm updating the local timestamps, but I'd see that being done by the fire and forget function when it has don its job - it it fails the local ts will not be updated and thus the app will try again at the next poll.

The factory is below, thanks.

angular.module('schoolApp.services', [])
    .factory('Poller', function($http, $interval) {

    function doesConnectionExist() {
        //code to return true if phone can access internet
    }

    // connect to remote server to pull down a JSON which says when various content types (News, Calander etc) have been last updated
    // update a local copy of this JSON date in localstorage (as a string in masterFeedTimestamp) if there has been am update since last poll
    var pollerFunct = function() {  
        if (doesConnectionExist() === true) {
            $http({method: 'GET', url: "http://" + httpHost + "/master_timestamps.php"}).
                success(function(remoteTSObj, status, headers, config) {

                var updateLocalStorage = false; // flag if localstorage needs updating

                var localTSObj = JSON.parse(localStorage.getItem('masterFeedTimestamp'));

                // loop through each row of the JSON from the server and compare the timestamp to that contained in localstorage
                for (var key in remoteTSObj) {
                    if (remoteTSObj.hasOwnProperty(key)) {
                        // get timestamps of each content channel and compare - take action if remote data is newer than local 
                        var remoteItemTS= new Date(remoteTSObj[key].lastUpdate);
                        var localItemTS= new Date(localTSObj[key].localTS);

                        if (remoteItemTS.getTime() > localItemTS.getTime()) // convert each time to ms since epoch
                        {
                            console.log("<<<<<<<<<<<<<< ******* new data for *******>>>>>>>>>>> " + key);
                            localTSObj[key].localTS = remoteTSObj[key].lastUpdate; // update local timestamp object
                            updateLocalStorage = true;

                            // do something here to update each content channel - need unique routines per channel as different formats etc 
                            switch (key) {
                            case "CALANDER":
                                console.log("CALANDER SWITCH.");
                                break;
                            case "CONTACTS":
                                console.log("CONTACTS SWITCH");
                                break;
                            case "NEWS":
                                console.log("NEWS SWITCH");
                                break;
                            }
                        }
                        var itemTS = key + " " +remoteTSObj[key].lastUpdate;
                    } // END if (remoteTSObj.hasOwnProperty(key)) {
                }

                if (updateLocalStorage === true){
                    localStorage.setItem('masterFeedTimestamp',JSON.stringify(localTSObj));
                    console.log("*************** UPDATE LOCAL STORAGE ***************");
                    var updateLocalStorage = false;
                }
            }).
            error(function(data, status, headers, config) {
                console.log("poller ERROR:");
            });
        } // END if (doesConnectionExist() == true) TRUE
        else { 
            console.log("no internet connection");
        }
    } // END pollerFunct()

    var httpHost = "app.dev";
    var pollTimeout = 1 * 5  * 1000;

    pollerFunct(); // run on app startup, then every pollTimeout duration
    $interval(pollerFunct, pollTimeout);
}) // END factory Poller

UPDATE

I came across this post:

How can I 'fire and forget' a JS function? (do not wait for return)

Which suggests:

setTimeout(function() {
    myFunc(); 
},0);

And also webworkers

Would either of these be suitable in my case?

javascript
angularjs
cordova