Regex: Capturing all digits in a string, and returning as a new string of digits

Question

I am trying to capture all the digits of an input string. The string can also contain other characters like letters so I can't simply do [0-9]+.

I've tried /[0-9]/g but this returns all digits as an array.

How do you capture, or match, every instance of a digit and return as a string?

Answer 1

Just replace all the non-digits from the original string:

var s = "foo 123 bar 456";
var digits = s.replace(/\D+/g, "");

Answer 2

The other solutions are better, but to do it just as you asked, you simply need to join the array.

var str = "this 1 string has 2 digits";
var result = str.match(/[0-9]+/g).join(''); // 12