Making the move from sprinkling simple interactive Ajax controls into basic web applications to building feature rich clients with large JavaScript libraries brings with it some unique challenges. Among them is the need for better testing tools. The presenter will discuss some pros and cons of a few of the more popular web application testing tools: JSUnit, HtmlUnit, and Selenium. In addition presenter will present Envjs as a headless option to JSUnit. An example app written in Ext JS and Grails will provide a demo.