Email地址正则表达式，@符号前后限定字符

Question

I have a regexp that check for valid email.

/^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

how would I limit the number of character before @ to 64 and after @ to 64.

Answer 1

Here is a simple regex example:

/^[a-zA-Z]{7}$/

This expression means:

• A single character between AZ
• A single character between az
• Finally, matches exactly 7 times -> {7}

You can simply add your regex {64} to check if it's 64 character long or not.

Answer 2

Two options:

1. After your long regex test, do a second regex test for length:

   /^.{1,64}@.{1,64}$)$/

2. Prefix a positive lookahead to your regex:

   /(?=^.{1,64}@.{1,64}$)^(YOUR REGEX)$/