validating an email with regexp multiple conditions

Question

I am looking for a valid regexp for my email validation requirement. I tried several times, but it buggy.

here is my try: .*@[^\W_]+(?:[\w-]*[^\W_])

need to fit with:

xxx@_domain.com => invalid @ starts with _
xxx@domain_.com => invalid domain ends with _ 
[email protected] => invalid @ starts with - ( hypen)
[email protected] => invlaid domain ends with - (hypen)
[email protected] => invalid domain start with - (hypen)
[email protected] => invalid domain only contains numbers
[email protected] => valid domain contains both number and chars
[email protected] => valid
[email protected] => valid
[email protected] => valid
[email protected] =>
xxx@abc_efg.com =>  valid _ inside the chars
[email protected] => valid _ start with

any one help me?

See: https://stackoverflow.com/questions/20771794/mailrfc822address-regex — Niet the Dark Absol, Sep 06 '19 at 14:24
Try it like this `^[^\s\W-]+(?:[_-][^\s\W_])*@(?![\d._-]+\.[^\W_]+$)[^\W_]+(?:[_-][^\W_]+)*\.[^\W_]+$` https://regex101.com/r/LVWh7m/1 — The fourth bird, Sep 06 '19 at 14:34
@Thefourthbird - yours works. please place as answer to accept — 3gwebtrain, Sep 06 '19 at 16:20
@3gwebtrain The question is marked as duplicate. Does the duplicate contain a working solution for you? — The fourth bird, Sep 06 '19 at 16:50
And your regex make this valid, see the this [email protected]` - need to restrict with 2 or 3 letters after dot operator — 3gwebtrain, Sep 07 '19 at 02:52
@3gwebtrain I have added a slighty modified version as an answer for your requirements. — The fourth bird, Sep 07 '19 at 08:02

score 1 · Answer 1 · answered Sep 06 '19 at 14:26

1

If this email value comes from a HTML input, i think the best way is to just set the type property to email and let the browser do the hard work, but if this is not the case, you can check Regexr, there's some community regex already created and it's quite a useful tool

answered Sep 06 '19 at 14:26

Breno Prata

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He definetly has to check some online regexp tester. His expression fail to match any emails supplied. – user14063792468 Sep 07 '19 at 07:41
1

What I mean by “fails to match” is that it matches just about any string. – user14063792468 Sep 07 '19 at 07:42

score 1 · Accepted Answer · answered Sep 07 '19 at 08:00

For your specific requirements you might use

^\w+(?:[_-][^\W_]+)*@(?![\d._-]+\.[^\W_]+$)[^\W_]+(?:[_-][^\W_]+)*\.[^\W_]{2,3}$

Explanation

^ Start of string
\w+ Match 1+ word chars
(?:[_-][^\W_]+)* Repeat 0+ times matching - or - and 1+ word chars except _
@ Match literally
(?! Negative lookahead, assert what is on the right is not
- [\d._-]+\.[^\W_]+$ Assert only digits or any of ._- until the end of the string
) Close lookahead
[^\W_]+ Match 1+ times a word char except _
(?:[_-][^\W_]+)* Repeat 0+ times matching - or - and 1+ word chars except _
\.[^\W_]{2,3} Match . and 2-3 times a word char except _
$ End of string

Regex demo

Yes, perfect. Thanks for details – 3gwebtrain Sep 08 '19 at 05:05 — 3gwebtrain, Sep 08 '19 at 05:05

validating an email with regexp multiple conditions

2 Answers2