Hi Damion,

You can try calling API and receive JSON from back-end. Below code will assist for Media Folders. Then you can use JQuery to populate dropdown.

Hope that helps. Please let me know your views.

public class MediaController : UmbracoApiController
{       
    public IEnumerable<MediaItem> GetAllMediaFolder()
    {
var allFolders = Umbraco.TypedMediaAtRoot().DescendantsOrSelf("folder");
return allFolders.Select(x=>new MediaItem() {Id = x.Id, Name = x.Name});        
    }
}

public class MediaItem {
    public int Id {set; get;}
    public string Name {set; get;}
}

Regards,

Shaishav