As you might expect, a non-capturing group is not captured in the match. For example, if you want to match phone numbers, you might require that a whitespace character be before a phone number so that you don't match, for example, the end of a username like JohnSmith1234567890 as a valid phone number. For example, here's a regex written previously to match email addresses (JavaScript):

• var regex = /(?:^|\s|$)([a-zA-Z0-9.\+_-]+@[a-zA-Z0-9._-]+)/gi; 

The regex wants to make sure that there is whitespace before the email, but wants to match "name@email.com" not " name@email.com" with a leading space.

Note that--when using JavaScript, at least:

The entire match will always be group 0, you need to access that specific group (group 1 in this case since the first group is non-capture).

Source: https://stackoverflow.com/questions/18178597/non-capture-group-still-showing-in-match/1817862

More on non-capturing groups:

• https://stackoverflow.com/questions/3512471/what-is-a-non-capturing-group-what-does-do

More on regexes:

• https://www.256kilobytes.com/content/show/2891/tool-code-email-address-and-phone-number-extractor-using-javascript-code-to-extract-emails-and-phone-numbers-with-a-regular-expressions

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