Question 51470 in Javascript Question posted in
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Javascript Regex problems around braces

The following program I wrote

var textRegEx = /.{1,3}/g;
var text = "AUZ01A1";
var woohooMatch = text.match(textRegEx);
var finalResult = woohooMatch.join(' - ')

console.log(finalResult);

gives the output as:

Output:

AUZ - 01A - 1

I want the output to be AUZ - 01 - A1. How do I alter textRegEx to achieve this? I tried (2, 3} and some other things, but it doesn’t work. I am new to both javascript and regex. Can you please help?

Tags:

3

Answers


  1. 0

    You can use groups () to match pattern of 3,2,2 characters:

    var text = "AUZ01A1";
var textRegEx = /(.{3})(.{2})(.{2})/;
var woohooMatch = text.match(textRegEx);
var [ , ...matches] = woohooMatch;
var finalResult = matches.join(' - ');


console.log(finalResult);
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  2. 0

    Separate cases of 6/7, 8 and other by a simple switch statement:

    function format(string) {
  switch (string.length) {
    case 6:
    case 7:
      return string.match(
        /^(.{2,3})(.{2})(.{2})$/
      ).slice(1).join(' - ');
    break;
    case 8:
      return string.match(
        /^(.{7})(.)$/
      ).slice(1).join(' - ');
    default:
      return string;
  }
}

    Or, if you prefer a tricky regex in a terse function:

    function format(string) {
  const match = string.match(/^(?=.{6,8}$)(?:.{7}|.{2,3})(?=(.{1}$|.{2})(.{2})?$)/);
  return match ? (match[2] ? match : match.slice(0, -1)).join(' - ') : string;
}

    Explanation for the regex, the rest is left as an exercise for the reader:

    ^                # Match at the beginning of string
(?=.{6,8}$)      # a string of 6, 7 or 8 characters long, which consists of
(?:.{7}|.{2,3})  # a capturing group of either 7 or 2 to 3 characters
(?=              # followed by
  (.(?:.|$))     # a second capturing group of a character followed by another or the end of string
  (.{2})?        # and an optional capturing group of two characters.
  $              # right before the end of string.
)                #

    Try it on regex101.com.

    Try it:

    function format1(string) {
  switch (string.length) {
    case 6:
    case 7:
      return string.match(
        /^(.{2,3})(.{2})(.{2})$/
      ).slice(1).join(' - ');
    break;
    case 8:
      return string.match(
        /^(.{7})(.)$/
      ).slice(1).join(' - ');
    default:
      return string;
  }
}

function format2(string) {
  const match = string.match(/^(?=.{6,8}$)(?:.{7}|.{2,3})(?=(.{1}$|.{2})(.{2})?$)/);
  return match ? (match[2] ? match : match.slice(0, -1)).join(' - ') : string;
}

// Test cases
const strings = [...'1234567890'].map(
  (_, i, a) => a.slice(0, i + 1).join('')
);

console.log(strings.map(format1));
console.log(strings.map(format2));
    .as-console-wrapper {
  max-height: 100% !important;
}
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  3. 0

    For your format, you can use an alternation with capture groups.

    Then in the result, remove the full match and join the capture groups with -

    Note that a . matches any character. If you only want to match uppercase chars or digits, you can use a character class [A-Zd]

    ^(?:(.{2,3})(..)(..)|(.)(.{7}))$

    Explanation

    • ^ Start of string
    • (?: Non capture group for the alternatives
      • (.{2,3})(..)(..) 3 capture groups, where the first group has 2 or 3 chars
      • | Or
      • (.)(.{7}) 2 capture groups, where the first has a single char and the second group 7 chars
    • ) Close the non capture groups
    • $ End of string

    Regex demo

    const regex = /^(?:(.{2,3})(..)(..)|(.)(.{7}))$/gm;
const s = `AUZ01A
AUZ01A1
AUZ01A11`;

for (const match of s.matchAll(regex)) {
  const result = match.slice(1)
    .filter(Boolean)
    .join(' - ');
  console.log(result);
}
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