code: function getAndroidJSInterface(oWebViewInterface){
      var AndroidWebViewInterface = com.shripalsoni.natiescriptwebviewinterface.WebViewInterface.extend({
          /**
           * On call from webView to android, this function is called from handleEventFromWebView method of WebViewInerface class
           */
          onWebViewEvent: function(webViewId, eventName, jsonData){
              // getting webviewInterface object by webViewId from static map.
              var oWebViewInterface = getWebViewIntefaceObjByWebViewId(webViewId);
              if (oWebViewInterface) {
                  oWebViewInterface._onWebViewEvent(eventName, jsonData);
              }
          }
      });
      
      // creating androidWebViewInterface with unique web-view id.
      return new AndroidWebViewInterface(new java.lang.String(''+oWebViewInterface.id));
   }
docs: Factory function to provide instance of Android JavascriptInterface.