Implementing Java interface from JavaScript fails with a TypeError

This is invalid JavaScript:

new Object() {};

It is invoking a function with "new" but fails to terminate the statement, then an open curly brace indicates the start of an object literal (this is valid syntax in Java; it creates an anonymous subclass). The strange thing is that the Rhino interpreter won't complain, but it correctly throws an error in the browser's engine: "SyntaxError: missing ; before statement"

Try writing the implementation using object literal notation:

var impl = {
    run: function() {
        println('Hello, World!');
    }
};

Here's a working example:

import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

public class RhinoTest {
    private static final String JAVASCRIPT_SRC = 
            " var impl = { " +
            "     run: function() { " +
            "         println('Hello, World!'); " +
            "     } " +
            " }; ";

    public static void main(String[] args) throws Exception {
        ScriptEngineManager factory = new ScriptEngineManager();
        ScriptEngine engine = factory.getEngineByName("JavaScript");
        engine.eval(JAVASCRIPT_SRC);

        Object impl = engine.get("impl");
        Runnable r = ((Invocable) engine).getInterface(impl, Runnable.class);
        r.run();
    }
}