Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /^(?=(?P<LE10>(?:0[0-9]|1[0-9]|2[0-8]|3[0-7]|4[0-6]|5[0-5]|6[0-4]|7[0-3]|8[0-2]|9[0-1])))?(?:(?:X|(?P>LE10))-){9}(?:XXX|XX\d|X?(?P>LE10)|(?:19|28|37|46|55|64|7|3|82|91)[X\d])$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?=(?P<LE10>(?:0[0-9]|1[0-9]|2[0-8]|3[0-7]|4[0-6]|5[0-5]|6[0-4]|7[0-3]|8[0-2]|9[0-1])))?(?:(?:X|(?P>LE10))-){9}(?:XXX|XX\\d|X?(?P>LE10)|(?:19|28|37|46|55|64|7|3|82|91)[X\\d])$', 'gm') const str = `X-91-55-72-X-X-X-90-71-91X X-91-55-72-X-X-X-90-82-XXX X-91-55-72-X-X-X-90-82-XX7 X-91-55-72-X-X-X-90-82-X91 X-91-55-72-X-X-X-90-82-90 X-91-55-72-X-X-X-90-82-X91 X-91-55-72-X-X-X-90-82-917 X-91-72-X-X-X-90-82-917 Number of delimiters (8) incorrect X-91-55-7-X-X-X-90-82-91X 7 in first 9 is invalid X-91-55-72-X-X-X-X94-82-91X X94 in first 9 is invalid X-91-55-72-X-X-X-90-82-X last = X is not valid X-91-55-72-X-X-X-90-82-XX last = XX is not valid X-91-55-72-X-X-X-90-82-XXXX last = XXXX is not valid X-91-55-72-X-X-X-90-82-X92 last = X92 is not valid X-91-55-72-X-X-X-90-82-94 last = 94 is not valid X-91-55-72-X-X-X-90-82-62X last = 62X is not valid X-91-55-72-X-X-X-90-82-927 last = 927 is not valid `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions