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 = /(?:(\d{2})(?:0(?=(?:\1)1)|1(?=(?:\1)2)|2(?=(?:\1)3)|3(?=(?:\1)4)|4(?=(?:\1)5)|5(?=(?:\1)6)|6(?=(?:\1)7)|7(?=(?:\1)8)|8(?=(?:\1)9))|(\d)(?:09(?=(?:\2)10)|19(?=(?:\2)20)|29(?=(?:\2)30)|39(?=(?:\2)40)|49(?=(?:\2)50)|59(?=(?:\2)60)|69(?=(?:\2)70)|79(?=(?:\2)80)|89(?=(?:\2)90))|099(?=100)|199(?=200)|299(?=300)|399(?=400)|499(?=500)|599(?=600)|699(?=700)|799(?=800)|899(?=900)){4,}\d{3}/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:(\\d{2})(?:0(?=(?:\\1)1)|1(?=(?:\\1)2)|2(?=(?:\\1)3)|3(?=(?:\\1)4)|4(?=(?:\\1)5)|5(?=(?:\\1)6)|6(?=(?:\\1)7)|7(?=(?:\\1)8)|8(?=(?:\\1)9))|(\\d)(?:09(?=(?:\\2)10)|19(?=(?:\\2)20)|29(?=(?:\\2)30)|39(?=(?:\\2)40)|49(?=(?:\\2)50)|59(?=(?:\\2)60)|69(?=(?:\\2)70)|79(?=(?:\\2)80)|89(?=(?:\\2)90))|099(?=100)|199(?=200)|299(?=300)|399(?=400)|499(?=500)|599(?=600)|699(?=700)|799(?=800)|899(?=900)){4,}\\d{3}', 'gm') const str = `531131231331431587 zzz005006007008009010011012zzz 551651751851952052152287 571771871972087 582682882983083183283487 593393593693793893994094194387 564965065165265365487 575775875976076187 526826927027127227487 547747847948048187 518919019119219387 583183283383483583783984084184284387 zzz097098099100101102zzz zzz198199200201202zzz zzz297298299300301302zzz zzz396397398399400401zzz zzz497498499500501zzz zzz598599600601602603zzz zzz697698699700701zzz zzz796797798799800801zzz zzz898899900901902903zzz zzz200201202203204zzz zzz295296297298299zzz zzz296297298299300zzz 500000100200300487 599599699799899987 `; // 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