I'm still working on it, but Perl::Critic is good (I've been using it in vim for a while, which checks every time you save), strict and warnings is good (which would be enabled on any new Perl program, but I'm working with a 15 year old codebase, so enabling these automatically creates a bunch of new failing "tests" that need fixing). There's a few different ways to use Perl::Critic in tests, the most promising seems to be Test::Perl::Critic::Progressive, which allows gradual introduction of Critic-friendly code without turning your whole smoker page red. (Which for me, is a problem...we'd have hundreds of failing tests, which would be overwhelming and make it hard to spot tests that will affect users.)

Devel::NYTProf is great for spotting performance regressions.

And, since we're pushing out HTML as the result of our application scripts running, I've been working on integrating HTML::Lint (I had to patch it to allow HTML::Pluggable::HTML5 to work, but I've sent a pull request to Andy, so the next version will likely support HTML5) into our test suite. This will tell us if any script breaks in such a way that it produces invalid HTML.

For JavaScript, jslint and jshint exist. I haven't started integrating or experimenting with either, yet. Our JavaScript is pretty minimal at the moment (a few thousand lines vs 500k+ lines of Perl), so it's not a priority compared to the Perl, and the Perl stuff is still in progress. JavaScript also has strict, which can catch some common problems, like the global scope "this".

Some help on spellcheck like stuff in perl would be perl-critic and perl-tidy.

Beware using this on old code though.

http://search.cpan.org/~thaljef/Perl-Critic-1.123/lib/Perl/C... http://search.cpan.org/~shancock/Perl-Tidy-20140711/lib/Perl...

I know nothing on javascript.

For javascript, eslint (http://eslint.org/) is now what I use. It's more configurable than what has come before it and has good, clear documentation.

For JavaScript, I like jshint: http://jshint.com , as I heard jslint was too opinionated.