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

/
/
gmxX

Test String

Code Generator

Generated Code

const regex = /(\$) # Regexp for textmate dynamic variables #TM_( # BUNDLE_SUPPORT|COMMENT_(?:END|MODE|START)|CURRENT_(?:LINE|WORD)|DIRECTORY|FILE(?:NAME|PATH)| # LINE_(?:INDEX|NUMBER)|PROJECT_DIRECTORY|SCOPE|SELECTED_(?:FILE[S]?|TEXT)|SOFT_TABS|SUPPORT_PATH|TAB_SIZE #) (?: # BASIC # BASIC: Variable name, no brackets (?:(TM_[A-Z]+(?:_[A-Z]+)*)|([\d]))(?!\{) | # BRACKETED ([\{]) # BRACKETED: Variable name (?:(TM_[A-Z]+(?:_[A-Z]+)*)|([\d])) # BRACKETED: Post variable name expression (?: # Default keyword, single ([:].+?(?=[\}])) | # Default keyword, options ([\|].+?[\|](?=[\}])) | # Regular expression (?: ([\/]) (.+?(?=\/)) ([\/]) (.+?(?=\/)) ([\/]) # Flags # Not sure how to validate fully without back references? ([imx]{3}) (?=\}) ) | (?: ([\/]) ([^\/\}]+?) ( (?<![\\]{2}) [\/] ) ([^\/\}]+?) ( (?<![\\]{2}) [\/] ) # Flags # Not sure how to validate fully without back references? ([imx]{3}) ) | # Match to bracket (.+?(?=[\}]))? )? ([\}]) )/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(\\$) # Regexp for textmate dynamic variables #TM_( # BUNDLE_SUPPORT|COMMENT_(?:END|MODE|START)|CURRENT_(?:LINE|WORD)|DIRECTORY|FILE(?:NAME|PATH)| # LINE_(?:INDEX|NUMBER)|PROJECT_DIRECTORY|SCOPE|SELECTED_(?:FILE[S]?|TEXT)|SOFT_TABS|SUPPORT_PATH|TAB_SIZE #) (?: # BASIC # BASIC: Variable name, no brackets (?:(TM_[A-Z]+(?:_[A-Z]+)*)|([\\d]))(?!\\{) | # BRACKETED ([\\{]) # BRACKETED: Variable name (?:(TM_[A-Z]+(?:_[A-Z]+)*)|([\\d])) # BRACKETED: Post variable name expression (?: # Default keyword, single ([:].+?(?=[\\}])) | # Default keyword, options ([\\|].+?[\\|](?=[\\}])) | # Regular expression (?: ([\\\/]) (.+?(?=\\\/)) ([\\\/]) (.+?(?=\\\/)) ([\\\/]) # Flags # Not sure how to validate fully without back references? ([imx]{3}) (?=\\}) ) | (?: ([\\\/]) ([^\\\/\\}]+?) ( (?<![\\\\]{2}) [\\\/] ) ([^\\\/\\}]+?) ( (?<![\\\\]{2}) [\\\/] ) # Flags # Not sure how to validate fully without back references? ([imx]{3}) ) | # Match to bracket (.+?(?=[\\}]))? )? ([\\}]) )', 'gm') const str = `~~ Number Variables ~~~~~~~~~ Basic "\$0" Bracketed "\${1} Default Value "\${2:default}" Default Values "\${3|defaultA,defaultB|}" Regex Replace "\${4/find/replace/gmi}" ~~ Dynamic Variables ~~~~~~~~ Basic "\$TM_SELECTION_START" Bracketed "\${TM_SELECTION_END}" Default Value "\${TM_SELECTED_FILE:default}" Default Values "\${TM_SELECTED_TEXT|defaultA,defaultB|}" Regex Replace "\${TM_SELECTED_FILES/find/replace/gmi}" `; // 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