Regex for removing all but the first number from a string

Question

I'm looking for a javascript replace regex that will strip out everything but the first number in a string. (The last will also work as well, see my test cases below)

Given the following:

P1, PROTECTED 1
or
P3, PROTECTED 3
or
P10, PROTECTED 10

I need 1,3, or 10

I need to only return the first or last number. It'll be between 1 and 10. They're the same.

var foo = 'P10, PROTECTED 10';
foo.replace(/(\d+)/,'');

strips out the first number...I need the exact opposite

OP wants a replace not match here. There might be better dupe link but not this one. — anubhava
– anubhava, Commented Sep 2, 2022 at 5:53

CF_HoneyBadger · Accepted Answer · 2022-09-22 15:02:18Z

2

You can search using this regex:

^\D*(\d+).*

and replace with '$1' (capture group #1)

RegEx Demo

Code:

const arr = ['P1, PROTECTED 1',
'P3, PROTECTED 3',
'P10, PROTECTED 10'];

const re = /^\D*(\d+).*/m;

arr.forEach(el => console.log(el.replace(re, '$1')));

RegEx Breakup:

^: Start
\D*: Match 0 or more non-digits
(\d+): Match 1+ digits in capture group #1
.*: Match everything till line end

edited Sep 22, 2022 at 15:02

CF_HoneyBadger

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answered Sep 1, 2022 at 20:11

anubhava

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1 Comment

CF_HoneyBadger Over a year ago

foo= foo.replace(/^\D*(\d+).*/, '$1'); seems to have done it. thanks a lot!

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