REGEX unique numbers delimited by comma

Question

I am trying to validate a comma separated list of numbers 1-31 unique (not repeating).

i.e.

• 2,4,6,7,1 is valid input.

• 2,2,6 is invali

Answer 1

For a number range that exceeds 1 digit, just add word boundary's around
the capture group and the back reference.
This isolates a complete number.

This particular one is numb range 1-31

 ^                                       # BOS
 (?!                                     # Validate no dups
      .* 
      (                                       # (1 start)
           \b 
           (?: [1-9] | [1-2] \d | 3 [0-1] )        # number range 1-31
           \b 
      )                                       # (1 end)
      .* 
      \b \1 \b 
 )
 (?: [1-9] | [1-2] \d | 3 [0-1] )        # Unrolled-loop, match 1 to many numb's
 (?:                                     # in the number range 1-31
      , 
      (?: [1-9] | [1-2] \d | 3 [0-1] )
 )*
 $                                       # EOS

    var data = [
      '2,4,6,7,1',
      '2,2,6',
      '2,30,16,3',
      '2,',
      '1,2,3,2',
      '1,2,2,3',
      '1,2,3,4,5,6,7,8'
      ];
      
      data.forEach(function(str) {
        document.write(str + ' gives ' + /^(?!.*(\b(?:[1-9]|[1-2]\d|3[0-1])\b).*\b\1\b)(?:[1-9]|[1-2]\d|3[0-1])(?:,(?:[1-9]|[1-2]\d|3[0-1]))*$/.test(str) + '
');
      });