In fact, there is one little, simple, really easy thing to do which will save you a lot of time…
The first thing I tried to do was to create a “fake” HTML element and dump my message into the DOM. That was not the best possible experience because I was loosing the “debugging” experience (pause, display values, etc.) but I was able to have some information at least.
Then an idea struck my mind : why not changing the debugger type as I do when I debug C++/CX apps ? That was the solution!
To have the same user experience than the one in WinJS apps or classic web app, you just have to set the debugger type to “script” in your app project.
Even the Dom Explorer is available to find out elements in your page.
I knew that Visual Studio was a really great IDE but I think that this kind of feature is just awesome and enable us to have the best possible productivity.