# FAQ: Introduction to Form Validation - Regular Expressions

This community-built FAQ covers the “Regular Expressions” exercise from the lesson “Introduction to Form Validation”.

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## FAQs on the exercise Regular Expressions

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“The pattern `[^]*\d{3}[^]*\d{3}-\d{4}` will match the two example phone numbers.”

Why?

1 Like

Same question here…I have no idea.

Regex Is extremely important when it comes to validation of forms, which is what the overall lesson is about. I’m fuzzy on regex myself, so I wish they went more in depth on it…

As someone who works with regex a lot I’m very confused about the use of `[^]*` in this regex pattern. From what I can tell in my research this pattern is exclusive to Javascript and it seems to me like bad practise to teach people this when it’s not applicable elsewhere. In regex we would just use .* to match all characters of any type, and I see no reason to use `[^]*` outside of confusion to be honest. I would love to hear from the course creators as to why this has been done.

Also for @ajax1388235901 and @calnicklin, I appreciate that it’s very long after you asked, but just in case anyone else finds themselves here. `[^]*` matches any character an infinite number of times i.e. will select everything up until the next rule match. Then we have `\d{3}` which is saying to select 3 digits. Therefore taken together `[^]*\d{3}` is saying “Match everything up to and including the first 3 digits you find”. This is then the same for the next section. Then it’s matching the `-` character, and then 4 digits. All this taken together lets you match any string of numbers separated in a 3-3-4 configuration, hence why it’s able to match the phone numbers, despite them having different formatting.

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