my collegue and I try to build a Regex (Javascript) to validate an input field for a specific format. The field should be a comma seperated list of port declarations and could look like this:
TCP/53,UDP/53,TCP/10-20,UDP/20-30
We tried this regex:
/^[TCP/\d+,|UDP/\d+,|TCP/\d+\-\d+,|UDP/\d+\-\d+,]*[TCP/\d+|UDP/\d+|TCP/\d+\-\d+|UDP/\d+\-\d+]$/g
the regex matches, but also matches other strings as well, like this one:
TCP/53UDP53,TCP/10-20UDP20-30
Thanks for any guidance!
You don't need all those alternations, and the [ ] are not used for grouping like that. You can also make the - and digits part optional using grouping (?:...)?
To match that string format:
^(?:TCP|UDP)\/\d+(?:-\d+)?(?:,(?:TCP|UDP)\/\d+(?:-\d+)?)*$
The pattern matches:
^ Start of string(?:TCP|UDP) Match one of the alternatives\/\d+(?:-\d+)? Match / 1+ digits and optionally - and 1+ digits(?: Non capture group to repeat as a whole part
,(?:TCP|UDP)\/\d+(?:-\d+)? Match a , and repeat the same pattern)* Close non capture group and optionally repeat (If there should be at least 1 comma, change the * to +)$ End of stringAlternative: split up the string, use Array.filter and a relative simple RegExp for testing.
const valid = `TCP/53,UDP/53,TCP/10-20,UDP/20-30`;
const invalid = `TCP/53UDP53,TCP/10-20UDP20-30`;
console.log(`${valid} ok? ${checkInp(valid)}`);
console.log(`${invalid} ok? ${checkInp(invalid)}`);
function checkInp(str) {
return str.split(`,`)
.filter(v => /^(TCP|UDP)\/\d+(?:-\d+)*$/.test(v))
.join(`,`)
.length === str.length;
}