[criley2]

Prompt:

'I'm writing a nodejs javascript application and I need a regex to validate emails in my server. Can you write a regex that will safely and efficiently match emails?'

GPT4 / Gemini Advanced / Claude 3 Sonnet

GPT4: `const emailRegex = /^[a-zA-Z0-9._-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;` Full answser: https://justpaste.it/cg4cl

Gemini Advanced: `const emailRegex = /^[a-zA-Z0-9.!#$%&'+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)$/;` Full answer: https://justpaste.it/589a5

Claude 3: `const emailRegex = /^([a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,})$/;` Full answer: https://justpaste.it/82r2v

[dfawcus]

Whereas email more or less lasts forever (mailbox contents), and has to be backwards compatible with older versions back to (at least) RFC 821/822, or those before. It also allows almost any character (when escaped at 821 level) in the host or domain part (domain names allow any byte value).

So a Internet email address match pattern has to be: "..*@..*", anything else can reject otherwise valid addresses.

That however does not account for earlier source routed addresses, not the old style UUCP bang paths. However those can probably be ignored for newly generated email.

I regularly use an email address with a "+" in the host part. When I used qmail, I often used addresses like: "foo-a/b-bar-tat@DOMAIN". Mainly for auto filtering received messages from mailing lists.

[zaxomi]

Still doesn't support internationalized domain names.

[croemer]

Terrible answers as far as I can tell, especially Chat got would throw out many valid email addresses.