Urgent and probably REALLY simple

hey,
I am now officially brain dead, but I still have to deliver the site today.

so there is one thing that is holding me back… i have to format a string to fit in an url. the issue is that the string may contain linebreaks, i need to do a search and replace for them

I am using this:
stringname.split(pattern).join(replacement)

and I just need to know what pattern to use for the new line.

have tried newline and "
" to no avail