syntax:

RegExp.lastParen

description:

This property has the text matched by the last group, parenthesized sub pattern, in the last pattern search. RegExp.lastParen is equivalent to RegExp["$+"], for compatibility with PERL.

Read-only property.

see:

RegExp.$n

example:

var str = "one two three two one";

var pat = /(t.o)+\s(t.r)/

pat.exec(str);

   // RegExp.lastParen == "thr"