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 = /^(?(DEFINE)(?'word'(?:[a-zA-Z0-9!?'"&\.,+@%~$]|(?<! )-(?! ))+)(?'words'(?&word)(?: (?&word))*?)(?'nothe'(?<!, (?i:a))(?<!, (?i:the|les)))(?'ver_prefix'Rev|Proto|Alpha|Beta))(?'title'(?&words)(?&nothe))(?'subtitle' - (?&words))*?(?'upd' (?:Update|DLC - (?&words)))?(?'region' \((?:(?:A|As|B|C|Ch|Nl|E|F|G|Gr|Hk|I|J|K|No|R|S|Sw|U|Uk|Tw|W))+\))?(?'version' \[(?:(?:(?&ver_prefix) )?(?:(?'_ver'[\da-zA-Z]+)(?:\.(?&_ver))+|\d\d\d\d-\d\d-\d\d(?:T\d+)?)|(?&ver_prefix)( (?:[A-Z]|\d+|early))?)\])?(?'part' \(Dis(?:c|k) \d+\))?(?'language' \((?'_lang'(?:F-)?(?:Ja|En|Fr|De|Es|It|Nl|Ca|Fi|No|Sv|Da|Zh(?:-Hant|-Hans)?|Pt|Ru|Ko|Pl))(?:,?(?&_lang))*\))?(?'randomshit'(?: \[DEMO\])?(?'lossy' \[LOSSY\])?(?: \[Sample\])?(?: \(Promo\))?(?: \(Unl\))?)(?'features' \[(?'_feat'[a-zA-Z]+)(?:, ?(?&_feat))*\])?(?'ext'\.(?:gbc|gb|nsp|xci|(nkit\.)?rvz|gcz|wbfs|wad|gba|type|cia|3ds|nds|nes|sfc|smc|n64|z64|wux|gg|md|sms|iso|pce|chd))$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?(DEFINE)(?\'word\'(?:[a-zA-Z0-9!?\'"&\\.,+@%~$]|(?<! )-(?! ))+)(?\'words\'(?&word)(?: (?&word))*?)(?\'nothe\'(?<!, (?i:a))(?<!, (?i:the|les)))(?\'ver_prefix\'Rev|Proto|Alpha|Beta))(?\'title\'(?&words)(?&nothe))(?\'subtitle\' - (?&words))*?(?\'upd\' (?:Update|DLC - (?&words)))?(?\'region\' \\((?:(?:A|As|B|C|Ch|Nl|E|F|G|Gr|Hk|I|J|K|No|R|S|Sw|U|Uk|Tw|W))+\\))?(?\'version\' \\[(?:(?:(?&ver_prefix) )?(?:(?\'_ver\'[\\da-zA-Z]+)(?:\\.(?&_ver))+|\\d\\d\\d\\d-\\d\\d-\\d\\d(?:T\\d+)?)|(?&ver_prefix)( (?:[A-Z]|\\d+|early))?)\\])?(?\'part\' \\(Dis(?:c|k) \\d+\\))?(?\'language\' \\((?\'_lang\'(?:F-)?(?:Ja|En|Fr|De|Es|It|Nl|Ca|Fi|No|Sv|Da|Zh(?:-Hant|-Hans)?|Pt|Ru|Ko|Pl))(?:,?(?&_lang))*\\))?(?\'randomshit\'(?: \\[DEMO\\])?(?\'lossy\' \\[LOSSY\\])?(?: \\[Sample\\])?(?: \\(Promo\\))?(?: \\(Unl\\))?)(?\'features\' \\[(?\'_feat\'[a-zA-Z]+)(?:, ?(?&_feat))*\\])?(?\'ext\'\\.(?:gbc|gb|nsp|xci|(nkit\\.)?rvz|gcz|wbfs|wad|gba|type|cia|3ds|nds|nes|sfc|smc|n64|z64|wux|gg|md|sms|iso|pce|chd))$', 'gm') const str = `Amazing Spider Man (UE).gb Otto's Ottifanten - Baby Bruno's Nightmare (E) (En,Fr,De,Es).gb Pokemon Kristall (G).gbc A Hat in Time DLC - Nyakuza Metro [1.1.0].nsp Pokemon Card GB2 - GR Dan Sanjou! (J).gbc Asphalt 9 Legends [1.3.1].nsp Animal Crossing New Horizons DLC - Special Order Ticket Pocket Camp tie-in campaign.nsp Pokemon Pinball (E) (En,Fr,De,Es,It) [S,DMG].gbc Arcade Hits - Moon Patrol & Spy Hunter (UE) [DMG].gbc Daikatana (U) [Proto 2000-04-19] [DMG].gbc Hang Time Basketball (E) (Unl).gbc Pokemon Green (J) [1.0] (F-En).gb LSDJ [9.2.L].gb Keep Talking and Nobody Explodes Update [1.2.0].nsp Sonic Mania Plus [1.0.4] (En,Ja,Fr,De,Es,It,Zh).xci Spelunky [1.22.2a].nsp Chrono Cross (U) (Disc 1).chd Chrono Cross (U) (Disc 2).chd Fear Effect 2 - Retro Helix (E) (Disc 1) (En,Fr,De).chd Ren & Stimpy Show - Buckeroo\$! (U).sfc PGA European Tour Golf (E) [Beta B.29] (En,De).z64 007 - The World Is Not Enough (U) [Beta 21].z64 007 - The World Is Not Enough (U) [Beta 2.00].z64 Pokemon Yellow (UE) [C].gb Shadowgate 64 - Trials of the Four Towers (U) [Beta] (En,Es).z64 Mario Kart Wii (U) (En,Fr,Es) [LOSSY].wbfs`; // 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