FireCrystal: Understanding interactive behaviors in dynamic web pages

For developers debugging their own code, augmenting the code of others, or trying to learn the implementation details of interactive behaviors, understanding how web pages work is a fundamental problem. FireCrystal is a new Firefox extension that allows developers to indicate interactive behaviors of interest, and shows the specific code (Javascript, CSS, and HTML) that is responsible for those behaviors. FireCrystal provides an execution timeline that users can scrub back and forth, and the ability to select items of interest in the actual web page UI to see the associated code. FireCrystal may be especially useful for developers who are trying to learn the implementation details of interactive behaviors, so they can reuse these behaviors in their own web site.