Javascript - replace string between brackets, but the brackets should stay

Question

I'd like to replace character inside a string, e.g.

Drafts [2]

To:

Drafts [3]

This regex returns only Drafts 3:

str.replace(/\[(.+?)\]/g, 3)

Thanks for help in advance

Answer 1

Do you need something more than below?

 var num=2 // parse this from drafts [2]
 num++;
 var newstr=str.replace(/\[(.+?)\]/g, "["+num+"]")

Or the brackets can change to <> {} per input?

You can also give a function instead of the replace-string.

var str = "Drafts [2]";

function replacer(match, p1, p2, p3, offset, string) {
  return p1 + (1+parseInt(p2)) + p3;
}
var newstr=str.replace(/([\[(])(.+?)([\])])/g, replacer);
alert(newstr); // alerts "Drafts [3]"