I mean something like you call a REST API where you create fake data which is then visible on the production site.
To avoid this, you should mock AJAX calls.
If I understand correctly what your question is, it shouldn't be a problem. Since your JavaScript - which you are testing - is publicly accessible, the tests shouldn't do any harm. They cannot do anythin, what the users couldn't do anyways.
What can be a problem: if you produce sample data during running the tests, you are going to produce a lot of trash data in your production environment. But you shouldn't do it anyway - just mock AJAX calls and so on.
I think nowaday is not the idea one should "protect". These days everybody has many ideas. The real value today is to succesfully develop the idea into a product or service which delivers value.
So just start working on it, show it to other people, try to find somebody who works on it with you (a developer), and collect some feedback.
Don't be affraid! If it is really a good idea, it's surely gonna be copied by others. :)
Would you like to see this feature also in Chrome? I'm really a fan of this syntax, because it's so easy to read and understand what is really happening.