Testing web applications can be a difficult task with the many complexities involved with current web technologies. At one time it was possible to test web applications without needing to rely on javascript at all. For this you could leverage java's htmlunit or even httpunit to write unit tests based on the source of a webpage. Javascript support in htmlunit was not the least bit usable on the web applications that I tested at my previous job, so it was completely off the table for the current project I'm responsible for testing.

Some kind Ruby Enthusiasts built a tool called Watir (Web Application Testing in Ruby) which basically allows you to programmatically control a web browser (Specifically Microsoft Internet Explorer). From a Software Quality Assurance standpoint this allows the developers to automate much of what is typically a manual process.