Converting a line break

A long time ago I remember that I made a script where when I typed a entry in a form, and I used the return button on the keyboard, a line break would be inserted into the code. Anyone know how to go about this?

I’m pretty sure this was in JavaScript, if not…let me know a language you think it’s in. Thanks!

EDIT
Nevermind, I found a line of code on an old script and it was the nl2br() tidbit that did it.