Problem with \b in cyrillic (JavaScript Regex)

Question

I have this regex: (*UCP).*\bпроверка\b.*. And it works well on the regex101.com (https://regex101.com/r/9elF5c), but not in JavaScript.

const regex = /(*UCP).*\bпроверка\b.*/
console.log(regex.test('а проверка б'))

Can someone please explain what the problem is and how to fix it

In regex101.com you have PCRE flavor selected. If you switch to ECMAScript it doesn't work there, either. — Barmar, Aug 26 '21 at 23:20
The problem is most likely that JS doesn't treat Cyrylic letters as word characters. — Barmar, Aug 26 '21 at 23:20

score 0 · Accepted Answer · answered Aug 27 '21 at 08:38

Using (*UCP) is a modifier supported by PCRE.

The error in Javascript is because this syntax does not work (* The parenthesis is a special char and the * is a quantifier.

If the string should have whitespace boundaries on the left and right:

.*(?<!\S)проверка(?!\S).*

const regex = /.*(?<!\S)проверка(?!\S).*/
console.log(regex.test('а проверка б'))

1 Answers1