code: public int lastIndexOf(Object obj) {
          if (obj instanceof JavascriptObject) {
              return checkInteger(invokeJavascript("lastIndexOf", ((JavascriptObject) obj).getJSObject()), -1);
          }
          return checkInteger(invokeJavascript("lastIndexOf", obj), -1);
      }
docs: lastIndexOf() 	Search the array for an element, starting at the end, and returns its position