Add debug terminal/console

Just now I went to look at the help requests and I saw someone asking where can he find a debug console or another side to do his coding.
I've tried console.log before and apparently it doesn't work.
It would be helpful if a debug console is provided for more advanced users to do their debugging more easily.

And one more question. May I know what library is KhanAcademy using to teach javascript? Or is it made by KhanAcademy to teach beginners thus only available in the website?

No files, tests, or entry points are named. Start by locating the live-editor code that handles console.log and identify how browser output is currently surfaced; define the intended debug-console scope and its completion criteria before proposing an implementation.

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