How to domain lock an HTML5 game?

Let’s say I make a game and want it played exclusivley on my website. How would I go about locking this game to my domain and making it unplayable on other domains?

Unity has a feature like this and I was wondering what’s the easiest/best way to do the same with Unreal.

http://docs.unity3d.com/Manual/UnityWebPlayerandbrowsercommunication.html

You can already communicate between C++ and Javascript code Howto

Now, domain locking - what you can do in javascript is check the value of location.host proceed in C++ accordingly. This code can exist wherever you want to make the game unplayable.

Awesome. So there’s really no way to do this without coding? And if I do code, will it mess up any Blueprint only projects I currently have?