You will probably get hundreds of comments with unsolocited advice, but let me just say to checkout and setup JSLint: https://github.com/douglascrockford/JSLin

You will probably get hundreds of comments with unsolocited advice, but let me just say to checkout and setup JSLint: https://github.com/douglascrockford/JSLint https://github.com/douglascrockford/JSLint Setup and how you use it is more important than just using it. I run it in three places: 1) In my IDE (bound in vim on save, same in TextMate) 2) As a Git checking hook 3) In deployment / build scripts Turn all the warnings way up and it always catches redeclaration bugs. Set it up once and don't allow any code to get checked in or deployed with even a single warning present. I also pass all Javascript through the Google Closure Compiler, but with the lowest compilation setting, because it is very good at picking up small errors as well. (if anybody is interested in how to set this all up I can publish my configs and scripts)