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 = /^(=?202\d)(\d{0,3}[A-Z]{1,4}|[A-Z]{1,4}\d{1,3})([\dA-Z]{0,4})A/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(=?202\\d)(\\d{0,3}[A-Z]{1,4}|[A-Z]{1,4}\\d{1,3})([\\dA-Z]{0,4})A', 'gm') const str = `Matches R1 R2 R3 R4 R5 R6 2022A144A OK OK OK OK \\D\\d\\d\\d 20228BC3A OK OK OK OK \\d\\D\\D\\d 20228Z1DA OK OK OK OK \\d\\D\\d\\D 2022K2 A 20229999A NOK \\d\\d\\d\\d 2022B123A OK OK OK OK \\D\\d\\d\\d 20221B23A OK OK OK OK \\d\\D\\d\\d 202212B3A NOK NOK NOK OK OK \\d\\d\\D\\d 2022123BA NOK OK \\d\\d\\d\\D 2022ABCDA 2022K2 A Matches 100% as desired R 12 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w|\\d\\d\\w\\D|\\D\\D\\D\\D)A R 13 ^(=?202\\d)(\\d{0,3}[A-Z]{1,4}|[A-Z]{1,4}\\d{1,3})([\\dA-Z]{0,4})A Should match R1: 2022\\d\\D\\w\\wA R2: 2022\\D\\d\\w\\wA R3: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w)A R4: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w)A R5: 2022(\\d\\D\\w\\w|\\D\\d\\w\\w|\\d\\d\\D\\w|\\d\\d\\w\\D)A R 10 ^(=?202\\d)(\\d*[A-Z]|[A-Z]*)([\\dA-Z]{1,3})A R 11 ^(=?202\\d)(\\d{1,3}[A-Z]*)([\\dA-Z]{1,3})A R 12 ^(=?202\\d)(\\d{1,3}[A-Z]{1,3}|[A-Z]{1,3}\\d{1,3})([\\dA-Z]{0,3})A ^ Start of string (?=[a-z\\d]{8,}\$) Positive lookahead, assert 8 or more chars a-z or digits till end of string (?=\\d*[a-z]) Positive lookahead to assert at least a char a-z [a-z]* Match optional chars a-z \\d Match at least a single digit [a-z\\d]* Match optional chars a-z or digits \$ End of string Should not match R6: 2022([A-Z0-9]{1,4})A R7: 2022(\\d|\\w){1,3}\\wA <-- also matches 20229999A which it should not R8: 2022\\w\\w\\s\\sA R9 2022\\d\\d\\d\\dA`; // 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