Nashorn provides debugging capability to Netbeans and other IDEs, allowing creation of breakpoints, stepping through code, inspecting variables, etc.

However, Nashorn performs optimizations when compiling JavaScript code that causes parameters and scope variables that are not externally visible to be stored in local slots instead of actual scope objects. This makes these parameters and variables invisible to the debugger.

The proposed solution is to add an option to the Nashorn jjs command line tool and scripting engine to force all variables and parameters to be reified as properties of an actual scope object.