Regex empty string or email

Question

I found a lot of Regex email validation in SO but I did not find any that will accept an empty string. Is this possible through Regex only? Accepting either empty string or

Answer 1

matching empty string or email

(^$|^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.(?:[a-zA-Z]{2}|com|org|net|edu|gov|mil|biz|info|mobi|name|aero|asia|jobs|museum)$)

matching empty string or email but also matching any amount of whitespace

(^\s*$|^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.(?:[a-zA-Z]{2}|com|org|net|edu|gov|mil|biz|info|mobi|name|aero|asia|jobs|museum)$)

see more about the email matching regex itself:

http://www.regular-expressions.info/email.html

Answer 2

this will solve, it will accept empty string or exact an email id

"^$|^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$"

Answer 3

If you are using it within rails - activerecord validation you can set allow_blank: true

As:

validates :email, allow_blank: true, format: { with: EMAIL_REGEX }

Answer 4

This regex pattern will match an empty string:

^$

And this will match (crudely) an email or an empty string:

(^$|^.*@.*\..*$)

Answer 5

The answers above work ($ for empty), but I just tried this and it also works to just leave empty like so:

/\A(INTENSE_EMAIL_REGEX|)\z/i

Same thing in reverse order

/\A(|INTENSE_EMAIL_REGEX)\z/i

Answer 6

I prefer /^\s+$|^$/gi to match empty and empty spaces.

console.log("  ".match(/^\s+$|^$/gi));
console.log("".match(/^\s+$|^$/gi));