Let me elaborate here to explain better how this feature we can use. I am currently debugging a good chunk of JS code in order to port it to Splash. For this purpose I am running a local instance of Splash where I run the requests to  execute the JS and I use the printer.text() commands to debug this code by looking at the log.

Once the JS code works fine I can then point it a production Splash. Once we get to that point we can disable the debugging output either at the JS level (what I am doing right now) or we can add a log level setting to Splash..