I have a confession: I used to debug my scripts using alert(). I didn't know about the console, about breakpoints or profiling. I didn't know there was a better way.

We shall see how to debug code line-by-line, how to optimise HTTP requests and how to profile the performance of your code. Finally we shall introduce DevTools to the server, inspecting Node.JS scripts with node-inspector. You'll never need alert() again.