selenium javascript executor

String popupAlertId = popupAlert.getAttribute("id");

JavascriptExecutor js1 = (JavascriptExecutor) driver;
String jscript = "function data() { var data = Document.getElementById('"
+ popupAlertId
+ "').innerHTML; return data;} return data ();";
Object scriptOutput = js1.executeScript(jscript);
Logging.log.info("scriptOutput " + scriptOutput);