Named capture groups in regex for readable patterns

Name Your Groups Instead of Counting Them

Numbered groups break when you add or remove a group. Named groups solve this: use (?<name>pattern) in JavaScript (ES2018+) and (?P<name>pattern) in Python.

// JavaScript
const re = /^(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})$/;
const { groups } = '2024-06-15'.match(re);
console.log(groups.year);  // '2024'
console.log(groups.month); // '06'
console.log(groups.day);   // '15'

Named Groups in Replacements

// JavaScript — use $<name> in replacement string
'2024-06-15'.replace(re, '$<month>/$<day>/$<year>')
// => '06/15/2024'

Named groups are worth the extra syntax on any pattern you will maintain.