CODEWITHSUNDEEP
regex
Mini
Mini

Reputation: 157

Regular expression for length validation in email address

We have a textbox which accepts comma separated email address. The regular expression is

^(\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*\s*[,]?\b)*$.

However now I am unable to add a length validation to this expression. Each email address should not be more than 150 characters. I have tried 

^((\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)){1,150}\s*[,]?\b)*$.

But it doesn't work. Can you please modify the regex so that it also implements this validation too.

Upvotes: 3

Views: 13114

Answers (5)

Morodin
Morodin

Reputation: 121

Use a lookahead

/(?=^.{1,150}$)(your regex goes here)/

Upvotes: 5

Brendan
Brendan

Reputation: 938

I arrived here looking for a way to extend my ng-pattern for e-mail for an Angular form.

Taking Rorick's approach of checking for length separately, I found a much easier solution: just set ng-maxlength="150" in the input. Then you can customize an error message that tells the user that the e-mail is too long.

maxlength="150" works fine too, preventing any extra characters from being added to the field, but I liked that ng-maxlength tells you what's wrong rather than truncating your string.

Upvotes: 0

Aaron Digulla
Aaron Digulla

Reputation: 328770

Why use a regexp when you can simply check the length of the string? If you must, use a second regexp:

^.{1,150}$

Upvotes: 5

Rorick
Rorick

Reputation: 8953

I would rather not complicate this regex further and add explicit length check before checking that e-mail matches. In JavaScript it will be something like the following:

function validateEmail(email) {
    var regex = /^(\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*\s*[,]?\b)*$/;
    // 20 is used instead of 150 for sake of example
    return email.length <= 20 && regex.test(email);
}
// validateEmail("[email protected]") == true
// validateEmail("[email protected]") == false

By the way, dot after $ in your regex seems to be a mistake, so I skipped it in my snippet.

Upvotes: 1

Sachin R
Sachin R

Reputation: 11876

^([a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]){0,70}$

Upvotes: 0

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