Question

When I run this java code, i am able to get the values of variables define outside the function, but i am unable to get the values of variable define inside the function. how to access these variable values?

import org.mozilla.javascript.Context;
import org.mozilla.javascript.Function;
import org.mozilla.javascript.Scriptable;


public class JSFunctionTest {

public static void main(String args[]) {

    String code = "var name='nc',global_a = 'jill'; " + "\n"+
            "function myfunc(b) { " + "\n"+
            "var local_a = 1;" + "\n"+
            "global_a = 'jack';" + "\n"+
            " return b;" + "\n"+
            "}"; 

    Context context = Context.enter();
    context.setGeneratingDebug(true);
    context.setOptimizationLevel(-1);

    Scriptable scope = context.initStandardObjects(); 

    context.evaluateString(scope, code, "code", 1, null);
    //getting values of varables
    System.out.println("var name:"+scope.get("name", scope));
    System.out.println("var global_a:"+scope.get("global_a", scope));
    System.out.println("var local_a:"+scope.get("local_a", scope));//not found becase function wasnt run

    //calling the function.
    Object fObj = scope.get("myfunc", scope);
    if (!(fObj instanceof Function)) {
        System.out.println("myfunc is undefined or not a function.");
    } else {
        Object functionArgs[] = { "nc" };
        Function f = (Function)fObj;
        Object r = f.call(context, scope, scope, functionArgs);
        String report = "myfunc('nc') = " + Context.toString(r);

        //trying to access global and local a after calling function
        System.out.println("var global_a:"+scope.get("global_a", scope));//values is changed, because this is defined out side the function.
        System.out.println("var local_a:"+scope.get("local_a", scope));// still not found,after running the function.

        System.out.println(report);
    }

}

}

Answer 1

I was able to resolve this, by implementing a debugger using the debug API in Rhino.

1. Implement your own debugger and debugframe classes.
2. Hook them to your context using setDebugger() method
3. in the DebugFrame class, I have implemented. cache the scope object in the onEnter method.
4. in the onLineChange method, you can get the local variables using ScriptableObject.getProperty() passing the cache scope object and giving the names