Regex to not allow particular special characters at start or end of email name in email address-CodePudding

I have the following regex condition for email address.

var value = /^[a-zA-Z0-9._-] @[a-zA-Z0-9] \.[a-zA-Z{2,}$/

But I dont want the name to start or end with period(.) or underscore(_) or hyphen (-) and this given special characters should include in middle only.

for eg :

            [email protected] Invalid
             [email protected] Invalid
              [email protected] Invalid
              [email protected] Invalid
              [email protected] Invalid
              [email protected] Invalid
              [email protected] Invalid
              [email protected] Invalid
              [email protected] Valid
              [email protected] Valid
              [email protected] Valid

I am trying to figure out the solution and learn in the process.

CodePudding user response：

You can use

var value = /^[a-zA-Z0-9] (?:[._-][a-zA-Z0-9] )*@[a-zA-Z0-9] \.[a-zA-Z]{2,}$/

Details:

^ - start of string
[a-zA-Z0-9] - one or more letters/digits
(?:[._-][a-zA-Z0-9] )* - zero or more occurrences of ./_/- and then one or more letters/digits
@ - a @ char
[a-zA-Z0-9] - one or more letters/digits
\. - a dot
[a-zA-Z]{2,} - two or more letters
$ - end of string.

See the regex demo.