javascript - Get string inside parentheses, removing parentheses, with regex

Question

I have these two strings...

var str1 = "this is (1) test";
var str2 = "this is (2) test";

And want to write a RegEx to extract what is INSIDE the parentheses as in "1" and "2" to produce a string like below.

var str3 = "12";

right now I have this regex which is returning the parentheses too...

var re = (/((.*?))/g);

var str1 = str1.match(/((.*?))/g);
var str2 = str2.match(/((.*?))/g);

var str3 = str1+str2; //produces "(1)(2)"

Answer 1

Like this

Javascript

var str1 = "this is (1) test",
    str2 = "this is (2) test",
    str3 = str1.match(/((.*?))/)[1] + str2.match(/((.*?))/)[1];

alert(str3);

On jsfiddle

See MDN RegExp

(x) Matches x and remembers the match. These are called capturing parentheses.

For example, /(foo)/ matches and remembers 'foo' in "foo bar." The matched substring can be recalled from the resulting array's elements 1, ..., [n] or from the predefined RegExp object's properties $1, ..., $9.

Capturing groups have a performance penalty. If you don't need the matched substring to be recalled, prefer non-capturing parentheses (see below).