The lastParen property represents the last parenthesized substring match.
It returns a string value for the last parenthesized substring.
<html> <body> <script language="JavaScript"> <!-- exp = new RegExp("(is)", "g"); str = "This is a test (is)"; myArray = exp.exec(str); document.write("The RegExp.lastParen is: " + "<b>" + RegExp.lastParen + "</b>"); --> </script> </body> </html>