The GWT developer plugin spans the gap between Java bytecode in the
debugger and the browser's JavaScript. There's no compiling of code to
JavaScript to view it in the browser. You can use the same edit-refresh-view
cycle you're used to with JavaScript, while at the same time inspect
variables, set breakpoints, and utilize all the other debugger tools
available to you with Java. And because GWT's development mode is now
in the browser itself, you can use tools like Firebug and Inspector
as you code in Java.