How do I match a number inside square brackets with regex

Question

I wrote a regular expression which I expect should work but it doesn\'t.

  var regex = new RegExp(\'(?<=\\[)[0-9]+(?=\\])\')

Javascript

Answer 1

This should work:

var regex = /\[[0-9]+\]/;

---

edit: with a grouping operator to target just the number:

var regex = /\[([0-9]+)\]/;

With this expression, you could do something like this:

var matches = someStringVar.match(regex);
if (null != matches) {
  var num = matches[1];
}