Doing this in the browser might be a little silly, or at least I can't immediately think of a good use, but I think using this in a node.js program as an easy way to template something out and render an image/pdf locally could be useful.

Of course, that's cool point!

JavaScript is the mainstream

http://en.wikipedia.org/wiki/Brainfuck

so the reasons all the same.

I was wondering the same thing. Why would anyone ever need to do something like this? What kind of project would this come useful?