Use RegExp to match a parenthetical number then increment it

I've been trying to find a way to match a number in a Javascript string that is surrounded by parenthesis at the end of the string, then increment it.

Say I have a string:

var name = "Item Name (4)";

I need a RegExp to match the (4) part, and then I need to increment the 4 then put it back into the string.

This is the regex I have so far:

b([0-9]+)$b

This regex does not work. Furthermore, I do not know how to extract the integer retrieved and put it back in the same location in the string.

Thanks.

---

The replace method can take a function as its second argument. It gets the match (including submatches) and returns the replacement string. Others have already mentioned that the parentheses need to be escaped.

"Item Name (4)".replace(/((d+))/, function(fullMatch, n) {
    return "(" + (Number(n) + 1) + ")";
});

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I can can only think of a way of doing it in three steps: Extract, increment and replace.

// Tested on rhino
var name = "Item Name (4)";
var re = /((d+))/;

match = re.exec(name);
number = parseInt(match[1]) + 1;
name = name.replace(re, "(" + number + ")");

The important parts of the pattern:

You need to escape the parens to match literal parens

You also need the to use parens to capture the number so that you can extract it from the match.

d matches a digit and is shorter and more common than writing out [0-9].

---

In order this pattern to work you shoud escape parenthesis. In addition b and $ are unneeded. Thus

var s = "Item Name (4)"; 
var match = /((d+))/.exec( s ); 
var n = Number(match[1])+1; 
alert( s.replace( /(d+)/, '('+n+')' ) );

Solution by david.clarke (tested)

"Item Name (4)".replace(/(([0-9]+))/, '('+(1+RegExp.$1) + ')');

But I think it is too concise

UPD : It turned out that RegExp.$1 can't be used as part of replace parameter, because it works only in Opera

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