Validate an mDNS address using pure Regex

Question

I need to validate whether a given string is a valid mDNS address. Examples of these are listed here:

a2aadd61-85d9-4be6-a36c-267ad65917d3.local
ccd58700-cdd5-4c1f-8098-5bc306f1ce77.local
bb4115cd-1f39-42b0-9433-e59533c9c771.local
3b382824-24bf-457a-a7d6-b6e25e4d79bf.local
9284cbaa-2933-45e3-9ae2-c0cccae54b68.local
619281fb-6426-44fa-8d0f-9e58ce415e3e.local
541d8a99-b1a5-46f4-96f1-e31f30b3cb99.local
2feb782f-ea40-4a37-b843-5b5b4fe1860e.local

Is this possible? I am new to regex and can't seem to find any regex examples for this particular string. This was my attempt at making a regex test:

let valid = 'a2aadd61-85d9-4be6-a36c-267ad65917d3.local';
let invalid = 'not-valid-233q4q22eqwr-q3rhHE02n333r4tsefs.local';

let regex = \([a-zA-Z1-9]+){8}-([a-zA-Z1-9]){4}-([a-zA-Z1-9]){4}-([a-zA-Z1-9]){12}\.local\;

regex.test(valid)

Answer 1

• First, the regex literal delimiters are not correct. It has to be slash and not backslash.

• Second, the + quantifier of the first character class of exactly eight characters is not needed (even wrong).

• Third, the sub-sequence of "4 characters plus dash" appears 3 times in a row. The OP's regex does not reflect this (it covers it just 2 times).

• Fourth, in addition to all that, the grouping into parenthesis is of no use. Thus, a regex which fixes and optimizes everything said needs to look close to ... /^[a-z\d]{8}(?:-[a-z\d]{4}){3}-[a-z\d]{12}\.local$/i.

const regXAddress =
  // see ... [https://regex101.com/r/6KWLm9/1]
  /^[a-z\d]{8}(?:-[a-z\d]{4}){3}-[a-z\d]{12}\.local$/i;

const testSample =
`a2aadd61-85d9-4be6-a36c-267ad65917d3.local
ccd58700-cdd5-4c1f-8098-5bc306f1ce77.local
bb4115cd-1f39-42b0-9433-e59533c9c771.local
3b382824-24bf-457a-a7d6-b6e25e4d79bf.local
9284cbaa-2933-45e3-9ae2-c0cccae54b68.local
619281fb-6426-44fa-8d0f-9e58ce415e3e.local
541d8a99-b1a5-46f4-96f1-e31f30b3cb99.local
2feb782f-ea40-4a37-b843-5b5b4fe1860e.local
2feb782f-e2a40-4a37-b843-5b5b4fe1860e.local
2feb78f-ea40-4a37-b8432-5b5b4fe1860e.local
2feb78f-ea40-4a37-b8432-5b5b4fe1860.local`;

console.log(
  testSample
    .split(/\n/)
    .map(address =>
      `'${ address }' is ${ regXAddress.test(address) ? '' : 'in' }valid`
    )
    .join('\n')
);

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