Javascript REGEX for Subdomain (Optional)

Question

I am looking for a REGEX (JS) that I can use to match all subdomains for a domain as well as the TLD domain in email addresses.

Here is an example:

I would like to be able to match any the following:

But not match

[email protected]

By default we use something like:

/(.*)@(.*)canada\.ca/gm

But this matches all of the above. Would ideally like a single REGEX that will accomplish all of this.

Why are you matching an @? The current pattern does not match any of the above — The fourth bird
– The fourth bird, Commented Mar 7, 2022 at 20:57
They are email addresses we are checking against. Left that off. sorry — VisualSP - DEV
– VisualSP - DEV, Commented Mar 7, 2022 at 20:59
Like this? ^[^\s@]+@(?:[^\s.]+\.)*canada\.ca$ regex101.com/r/etLosM/1 — The fourth bird
– The fourth bird, Commented Mar 7, 2022 at 21:01

The fourth bird · Accepted Answer · 2022-03-07 21:08:32Z

1

You could use

^[^\s@]+@(?:[^\s@.]+\.)*canada\.ca$

^ Start of string
[^\s@]+ Match 1+ chars other than a whitespace char or @
@ Match literally
(?:[^\s@.]+\.)* Match optional repetitions of 1+ chars other than a whitespace char, @ or dot, and then match the .
canada\.ca Match canada.ca (Note to escape the dot to match it literally
$ End of string

Regex 101 demo.

const regex = /^[^\s@]+@(?:[^\s@.]+\.)*canada\.ca$/;
[
  "[email protected]",
  "[email protected]",
  "[email protected]",
  "[email protected]",
].forEach(s => console.log(`${s} --> ${regex.test(s)}`));

edited Mar 7, 2022 at 21:08

answered Mar 7, 2022 at 21:06

The fourth bird

165k16 gold badges61 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

VisualSP - DEV Over a year ago

That works. Now I need to use it to learn from. Thank you

Gary Over a year ago

@VisualSP-DEV This is a pretty good site for visualizing regexes

VisualSP - DEV Over a year ago

Thanks, @Gary - I will look at that

Blindy · Accepted Answer · 2022-03-07 21:10:41Z

0

An easier way is to simply anchor canada to a word boundary using \b, that way you can use your regex pretty much word for word:

.*@.*\bcanada\.ca

answered Mar 7, 2022 at 21:10

Blindy

68k10 gold badges96 silver badges141 bronze badges

4 Comments

Gary Over a year ago

That would allow things like "[email protected]"

VisualSP - DEV Over a year ago

@Blindy - thanks, I will look at you solution as well.

Blindy Over a year ago

Well we're talking about regex here and parsing email addresses. No matter how good you are and how many pages of regex you write, it still won't be RFC-conforming. This is simple and it matches every one of the OP's test cases :)

Gary Over a year ago

I think this falls outside the spirit of the question by matching other valid/simple domains. But I agree with your overall point.

Collectives™ on Stack Overflow

Javascript REGEX for Subdomain (Optional)

2 Answers 2

3 Comments

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related