SWF Studio V3 allows you to load and call JScript functions from Flash which offers some advantages over ActionScript and allows you to perform tasks that would be difficult or impossible to do with ActionScript alone.
You can call JScript functions from Flash using the Script commands.
One of the biggest advantages JScript offers is the ability to create and execute code at runtime. You can write JScript functions and make them part of your application or you can load and execute JScript code on the fly.
See the JScript Users Guide on the Microsoft web site for more detailed information about what you can do with JScript and be sure to check out Calling JScript from Flash to see how easy it is to start using JScript in your own applications.