Capturing groups are one of the most useful feature of regular expressions, and the possibility to name groups make them even more powerful.

How it works?

Imagine that you have a list of files that are named in a structured way, for example 1_create_users_table.sql, where the number represents some code and the following part a name. So it is [code]_[name].sql.

Now instead of parsing those file names, maybe using split or something, you could just write a regex to precisely identify each portion of the string and return them individually? Easy peasy with named capturing groups!

const regex = /(?<code>\d+)_(?<name>\S+)\.sql/;
const fileName = '1_create_users_table.sql';
const groups = fileName.match(regex).groups;
console.log(groups.code);  // 1
console.log(groups.name);  // create_users_table

As you can see in the example above, we can specify the name of a capturing group by using the (?<group-name>...) syntax and the regex engine does the job of returning each group name into the groups property. It is that simple!

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