[A-Za-z0-9]{1,254}
Indicates ,
any character of: 'A' to 'Z'
, 'a' to 'z'
,
'0' to '9'
(between 1 and 254 times
(matching the most amount possible)),
Edit: If you need @
at the end try with the regex [A-Za-z0-9]{1,254}@
1
solved Filter input amount at specific points in regex? [closed]