unfortunately, there is currently no properly supported way to do that. You can of course fetch keystrokes, but that will only work in the local install. On the web platform, the unfortunate answer is that there is no way to achieve that.
We had discussed such an editor in the last performance show but I just noticed that this has not made its way even to the backlog. Therefore, I just added a new story to provide just that. However, the story is just created, not yet in the sprint nor in the master branch.