Chat API (JavaScript) - "Authentication Required" when making API requests

Hi,

I am having an issue whenever I call a Chat API method I get a browser basic authentication box asking "The server https://dev.liveperson.net:443 requires a username and password. The server says: dev.liveperson.net.". I'm not sure why this is showing, is it to do with running on localhost, or I haven't configured a domain, or something in my init code that I'm missing?

Currently I am creating a new Chat API object, then when it's onInit callback fires I call the getAvailableSlots() method. The init appears to work but then calling getAvailableSlots() shows the login box pictured above.

var chat = new window.lpTag.taglets.ChatOverRestAPI({     
     appKey: APP_KEY,     
     lpNumber: SITE_ID,
     onInit: function() {
          console.log('init', data);
          api.availableSlots();
     } });
 
var api = {
     availableSlots: function() {
          if (!chat) { return false; }
 
          var request = chat.getAvailableSlots({
               success: delegate.availableSlots.success,
               error: delegate.availableSlots.error,
               context: delegate
          });
          if (request && request.error) {
               return request.error;
          }
          return true;
     }
}

I am still using a development application key, with a development "Medium sized business" test account, and I am running the code on localhost.

Please let me know if you need more details or if anyone knows what's going on. I'm guessing I have missed something obvious.

Thanks