更新设计正则表达式以进行电子邮件验证

Question

I'm currently using Devise regex :

/\\A[^@\\s]+@[^@\\s]+\\z/

Which is simple and sort. But, it doesn't filter email like example@example..com .

An alternative to that is URI::MailTo::EMAIL_REGEXP :

/\\A[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])?)*\\z/

Which will filter valid domains like hans@über.com .

I'm not good at regex, but is there something better or how an I add a double dot validation in the first one with Devise.

Answer 1

You may refactor your regex as

/\A[^@\s]+@[^@.\s]+(?:\.[^@.\s]+)*\z/ # If you want to allow name@domain
/\A[^@\s]+@[^@.\s]+(?:\.[^@.\s]+)+\z/ # If you want to require at least one dot after @

Here,

• \\A - start of string
• [^@\\s]+ - a negated character class that matches 1 or more characters other than @ and whitespace
• @ - a @ char
• [^@.\\s]+ - 1 or more characters other than @ , . and whitespace
• (?:\\.[^@.\\s]+)* - 0 or more occurrences (or 1 or more if + is used at the end) of
  • \\. - a dot
  • [^@.\\s]+ - 1 or more characters other than @ , . and whitespace
• \\z - end of string.

See regex #1 demo and regex #2 demo .