A "browser" can't run things.

Actually most browsers do run things, be it javascript, java or the oh-so-scary MS vbscript stuff. Not to mention Emacs, which is among other things a browser and can run almost anything.

This said, you could write a perl interpreter written in javascript, or even better a javascript linux-emulation layer and execute perl on top...

I'd offer more solutions to this problem, but this one-sleeved shirt makes typing very hard.