JavaSriptException now inherits from RhinoException which inherits from RuntimeException and as such it does not necessary to declare it.
Moreover, it is wrong to use it for the documentation purpose since a script can also throw EcmaError and WrappedException and a proper documentation would require to document those exceptions as well. But since almost all Rhino functions can potentially execute script code it means that wast majority of functions would bear the declarations, not only code overriding or calling explicitly Function.call/construct. And then the throw declarations would bring no information if it always would be "throws RhinoException". Thus it is better not to litter sources with the declarations at all.