[regex] Regex empty string or email

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 email only? I want to have this on Regex only.

This question is related to regex email string

The answer is

Don't match an email with a regex. It's extremely ugly and long and complicated and your regex parser probably can't handle it anyway. Try to find a library routine for matching them. If you only want to solve the practical problem of matching an email address (that is, if you want wrong code that happens to (usually) work), use the regular-expressions.info link someone else submitted.

As for the empty string, ^$ is mentioned by multiple people and will work fine.

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


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

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

console.log("  ".match(/^\s+$|^$/gi));_x000D_

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


Same thing in reverse order


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


matching empty string or email


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


see more about the email matching regex itself:


Examples related to regex

Why my regexp for hyphenated words doesn't work? grep's at sign caught as whitespace Preg_match backtrack error regex match any single character (one character only) re.sub erroring with "Expected string or bytes-like object" Only numbers. Input number in React Visual Studio Code Search and Replace with Regular Expressions Strip / trim all strings of a dataframe return string with first match Regex How to capture multiple repeated groups?

Examples related to email

Monitoring the Full Disclosure mailinglist require(vendor/autoload.php): failed to open stream Failed to authenticate on SMTP server error using gmail Expected response code 220 but got code "", with message "" in Laravel How to to send mail using gmail in Laravel? Laravel Mail::send() sending to multiple to or bcc addresses Getting "The remote certificate is invalid according to the validation procedure" when SMTP server has a valid certificate How to validate an e-mail address in swift? PHP mail function doesn't complete sending of e-mail How to validate email id in angularJs using ng-pattern

Examples related to string

How to split a string in two and store it in a field String method cannot be found in a main class method Kotlin - How to correctly concatenate a String Replacing a character from a certain index Remove quotes from String in Python Detect whether a Python string is a number or a letter How does String substring work in Swift How does String.Index work in Swift swift 3.0 Data to String? How to parse JSON string in Typescript