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 = /^(?<Monthswith31>31(?<s1>\/|\.|-)(0?[13578]|1[02]|(Jan|Mar|May|Jul|Aug|Oct|Dec))\g<s1>(?<Year>19[0-9][0-9]|200[0-7]))$|^(?<Monthswith29or30>(29|30)(?<s2>\/|\.|-)(0?[1,3-9]|1[0-2]|(Jan|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\g<s2>(?<Year2>19[0-9][0-9]|200[0-7]))$|^(?<Allmonthswith28>(0?[1-9]|1[0-9]|2[0-8])(?<s3>\/|\.|-)(0?[1-9]|1[0-2]|(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\g<s3>(?<Year3>19[0-9][0-9]|200[0-7]))$|^(?<FebLeapYears>29(?<s4>\/|\.|-)(0?2|Feb)\g<s4>(19([02468][048]|[13579][26])|200[04]))$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?<Monthswith31>31(?<s1>\\\/|\\.|-)(0?[13578]|1[02]|(Jan|Mar|May|Jul|Aug|Oct|Dec))\\g<s1>(?<Year>19[0-9][0-9]|200[0-7]))$|^(?<Monthswith29or30>(29|30)(?<s2>\\\/|\\.|-)(0?[1,3-9]|1[0-2]|(Jan|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\g<s2>(?<Year2>19[0-9][0-9]|200[0-7]))$|^(?<Allmonthswith28>(0?[1-9]|1[0-9]|2[0-8])(?<s3>\\\/|\\.|-)(0?[1-9]|1[0-2]|(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec))\\g<s3>(?<Year3>19[0-9][0-9]|200[0-7]))$|^(?<FebLeapYears>29(?<s4>\\\/|\\.|-)(0?2|Feb)\\g<s4>(19([02468][048]|[13579][26])|200[04]))$', 'gm') const str = `02/Apr/2006 23/10/1996 13/10/2000 Right Ones 28/05/2000 01/01/2000 1/1/2000 01/Jan/2000 31/01/ 31/Jan/2000 31.Jan.2000 31-Jan-2012 30/Mar/2000 29/Apr/2000 29/10/2000 29/02/2000 20/Apr/1983 28/02/2000 01/1/2000 01/Jan/2000 01/1/01 01/Jan/01 29/02/2000 29/Feb/2000 01/01/2020 #1st Jan 07/03/2020 #3 July 12/2/2020 #2 December 23/4/2020 #23 April Wrong Ones 31/04/2000 29/Feb/2001 13/13/2000 30/Feb/2000 25/February/2000 32/01/2000 32/Jan/2000 `; // 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