Constructing a regex with three subpatterns and a maximum length of 28 characters

Question

I need to create an expression that fit this requirements :

• The string must be composed by 3 substring

• The first substring accept 0-9a-zA-Z, the minimum length is 1 and there is notte max length

• The second substring must be " - "

• The last have The first's one same condition

• Total maximum string length must be 28 chars

It is possible to accomplish this requirement with Regex?

Answer 1

Following regex should work fine:

/(?=^.{3,28}$)[^\W_]+\-[^\W_]+/

var array = [
  "123456790-123456789012345678",
  "123456790-1234567890123456789",
  "adsd-dsds"
];
var re = /(?=^.{3,28}$)[^\W_]+\-[^\W_]+/;
array.forEach(e => console.log(re.test(e) ? e.match(re)[0]: "match failed"));

Breakdown shamelessly copied from regex101.com:

• Positive Lookahead (?=^.{3,28}$)
  • ^ asserts position at start of a line
  • .{3,28} matches any character (except for line terminators)
  • {3,28} Quantifier — Matches between 3 and 28 times, as many times as possible, giving back as needed (greedy)
  • $ asserts position at the end of a line
• Match a single character not present in the list below [^\W_]+
  • + Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
  • \W matches any non-word character (equal to [^a-zA-Z0-9_])
  • _ matches the character _ literally (case sensitive)
  • \- matches the character - literally (case sensitive)
• Match a single character not present in the list below [^\W_]+
  • + Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)
  • \W matches any non-word character (equal to [^a-zA-Z0-9_])
  • _ matches the character _ literally (case sensitive)