If you are familiar with JavaScript then you should be able to be productive with Perl pretty quickly.

I recommend the reading "Programming Perl" (the Camel book) or "Learning Perl", both from O'Reilly press.

If you are using a Mac or Linux system, you probably already have Perl installed, so there is no setup to start using it.

I think the Bash vs Perl example there is not exactly fair, since in Perl you're not assigning to ls_output first. You could do the same in bash, and it's arguably just as expressive:

    (( `ls | wc -l` > 100 )) && echo "many files" || echo "few files"