Function object cannot be called with different context

Frantzius, Jörg Joerg.Frantzius at
Mon Jan 30 10:28:14 UTC 2017


in my code, I get hold of a function object from some 3rd party Javascript code, and I need to execute that function within a new context, i.e. make new ENGINE_SCOPE bindings available to it. unfortunately does not allow to define a context to execute in, so I tried to workaround by calling the function from a CompiledScript that in turn can be executed with a custom context:

    public void testJsFunctionWithContext() throws ScriptException {
        ScriptEngine engine =  new ScriptEngineManager().getEngineByName("JavaScript");
        jdk.nashorn.api.scripting.ScriptObjectMirror jsFunction = (ScriptObjectMirror) engine.eval("function test() {return foo;}");

        ScriptContext context = new SimpleScriptContext();
        context.setAttribute("foo", "bar", ScriptContext.ENGINE_SCOPE);
        context.setAttribute("fn", jsFunction, ScriptContext.ENGINE_SCOPE);

        // does work: access context directly
        CompiledScript contextWrapper = ((Compilable) engine).compile("foo");
        String result = (String) contextWrapper.eval(context);
        assertEquals("bar", result);

        // does not work: access context from within function ("foo" is not defined)
        contextWrapper = ((Compilable) engine).compile("fn()");
        result = (String) contextWrapper.eval(context);
        assertEquals("bar", result);

Is there some mistake I made here, or is it simply not possible for a function object to access variables from a new context?
If that’s really not possible, is there maybe a way of turning a function object into a CompiledScript object, which can then be evaluated with a new context?

Thanks for any help,


Dipl. Inf. Jörg von Frantzius, Technical Director

E-Mail joerg.frantzius at

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