First, note that on your browser console you still can type code and run then, which is a powerful tool for testing small pieces of code. So this post if for another scenario where you really want to type or load a full .js full.
Let's see it in action before anything else:
To make it work we need the .EvaluateScriptAsync() from the other post and a place where we can type our code, so I decided to use ScintillaNET package (NuGet) to edit the code. The UI is almost a direct copy & paste from their sample, with some small changes: the bottom Run button (or Ctrl+R) and the text box with results. The code also integrates with the Cefsharp browser to run the code.
Enjoyed the sample tool? Suggestions?