Why this polling stops working after idling for some time?

Question

I am using AngularJS to constantly poll for new data through HTTP POST. An alert will be sent when new data is received. The code which is inside a controller looks something like this;

    var poll = function() {
        $http.get('phones.json').success(
            function(data)
            {
                new_val = data.val;
                if ( (new_val!== old_val) )
                {
                    $window.alert("AlertEvent");                        
                }

                old_data = new_val;
                $timeout(poll, 500);
            }
        );
    };
    poll();   

This code works when the html page is refreshed. Working means when phones.json is changed, an alert will appear. However, if I leave the page on for, say 30 minutes, and come back later, it stops working. I have to refresh the page to get it working again.

What else did I miss out? What did I do wrong? Could it due to some caching mechanism?

Thank you very much.

EDIT: I found the cause. It is indeed due to the browser reading from cache. I can see this using Chrome Developer tools. How can this caching be disabled for this html page only?

Answer 1

You may be able to bust the cache by doing something like this:

 $http.get('phones.json?v=' + Date.now())

Depending on how your back-end is set-up you may need to adjust it to accept that.