Regex email check not working correctly

Question

I have a problem with my regex. I didn't test this before. I have the following regex:

^(?:(?:[a-z])+(.|_)?(?!\.))*\w@(?:(?:[a-z])+(-|.)?(?!\.))*\w\.\w{2,}$

Now, my email validation halfly works. Here are some tests (according to regex101):

test -- invalid
test@ -- invalid
test@test -- invalid
test@test. -- invalid
test@test.de -- valid
test@test.de. -- invalid
test@test@test.com -- valid
test...test@test.com -- invalid

So, more than one @ can be used which is invalid for an email.

I kind of cannot see what I'm doing wrong.

NOTE:

I know there's a stackoverflow question that has a method on how to validate email with regex, HOWEVER: I'd like to know what I did wrong so I can learn from it.

Possible duplicate of [Validate email address in JavaScript?](http://stackoverflow.com/questions/46155/validate-email-address-in-javascript) — Andrey Korneyev, Mar 30 '17 at 08:53
@AndyKorneyev I'd rather know what I did wrong so I can learn from it. — Joshua Bakker, Mar 30 '17 at 08:54

score 1 · Answer 1 · answered Mar 30 '17 at 09:10

1

I found out the problem myself. The following regex does work:

^(?:(?:\w)+(\.|_)?(?!\.))*\w@(?:(?:[a-z])+(-|\.)?(?!\.))*[a-z]\.[a-z]{2,}$

I changed (.|_) into (\.|_) and (-|.) into (-|\.) to use . literally as a period and not as an 'all character "wildcard"'. I changed \w\.\w{2,} in [a-z]\.[a-z]{2,} to disallow _ in the last part.

answered Mar 30 '17 at 09:10

Joshua Bakker

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`(\.|_)` is better replaced with `[._]`. And no need escaping the dot then. – Wiktor Stribiżew Mar 30 '17 at 09:14
@WiktorStribiżew Thanks for the tip. – Joshua Bakker Mar 30 '17 at 09:17

Regex email check not working correctly

1 Answers1