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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

Substitution

Processing...

Code Generator

Generated Code

const regex = /^([ ]{6})(- )((?!name)\w+[:](?:[ ]*(?=\n\1[ ]{4}\S)|[ ]*\S.+))((?:\n\1[ ]{2}.+)*?)(?:\n(\1[ ]{2})(name[ ]*[:])((?:[ ]*(?![>|])\S.+\b)|(?:(?:[ ]*[>|])?\n\5[ ]+.+)*))[ ]*$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^([ ]{6})(- )((?!name)\\w+[:](?:[ ]*(?=\\n\\1[ ]{4}\\S)|[ ]*\\S.+))((?:\\n\\1[ ]{2}.+)*?)(?:\\n(\\1[ ]{2})(name[ ]*[:])((?:[ ]*(?![>|])\\S.+\\b)|(?:(?:[ ]*[>|])?\\n\\5[ ]+.+)*))[ ]*$', 'gm') const str = `// YAML Textmate grammar name property hoister // Moves a later \`name\` key value pair in multi value block definition to the // top of its // // # Notes // - Indent size is assumed to be 2. // - Indent level of names being hoisted is controlled by capture group \$1, // which is later referenced by \$5, the indent level of all other properties // - Other properties can be hoisted by replacing the two instances of \`name\` // in the pattern. A couple inputs for simple nested, folded, and literal values // (immediately after these notes) seem to work. // - Syntax level comments in captures will probably need to be rearranged after // applying this, and worst case (especially comments lower indents) break matching - match: '\\s*(\\,)\\s*' name: 'Testing': Regex101.Debug.Nested.Name - match: '\\s*(\\,)\\s*' name: 'Testing': Regex101.Debug.Nested.Name.TrailingWhitespace - match: '\\s*(\\,)\\s*' # Comment name: 'Testing': Regex101.Debug.Nested.Name.TrailingWhitespace - match: '\\s*(\\,)\\s*' name: > Wow this is a long name? kind of sus - match: '\\s*(\\,)\\s*' name: | sus2 - name: meta.selector.stylus match: '\\s*(\\,)\\s*' - match: \\* name: meta.selector.stylus - match: '\\s*(\\&)([a-zA-Z0-9_-]+)\\s*' captures: '2': name: entity.other.attribute-name.parent-selector-suffix.stylus name: meta.selector.stylus - match: \\s*(\\&)\\s* name: meta.selector.stylus - captures: '1': name: punctuation.definition.entity.css match: '(\\.)[a-zA-Z0-9_-]+' name: entity.other.attribute-name.class.css - captures: '1': name: punctuation.definition.entity.css match: '(#)[a-zA-Z][a-zA-Z0-9_-]*' name: entity.other.attribute-name.id.css - captures: '1': name: punctuation.definition.entity.css match: >- (:+)(after|before|content|first-letter|first-line|host|(-(moz|webkit|ms)-)?selection)\\b name: entity.other.attribute-name.pseudo-element.css - captures: '1': name: punctuation.definition.entity.css match: >- (:)((first|last)-child|(first|last|only)-of-type|empty|root|target|first|left|right)\\b name: entity.other.attribute-name.pseudo-class.css - captures: '1': name: punctuation.definition.entity.css match: >- (:)(checked|enabled|default|disabled|indeterminate|invalid|optional|required|valid)\\b name: entity.other.attribute-name.pseudo-class.ui-state.css - begin: '((:)not)(\\()' beginCaptures: '1': name: entity.other.attribute-name.pseudo-class.css '2': name: punctuation.definition.entity.css '3': name: punctuation.section.function.css end: \\) endCaptures: '0': name: punctuation.section.function.css patterns: - include: '#selector' - captures: '1': name: entity.other.attribute-name.pseudo-class.css '2': name: punctuation.definition.entity.css '3': name: punctuation.section.function.css '4': name: constant.numeric.css '5': name: punctuation.section.function.css match: >- ((:)nth-(?:(?:last-)?child|(?:last-)?of-type))(\\()(\\-?(?:\\d+n?|n)(?:\\+\\d+)?|even|odd)(\\)) - match: '((:)dir)\\s*(?:(\\()(ltr|rtl)?(\\)))?' captures: '1': name: entity.other.attribute-name.pseudo-class.css '2': name: puncutation.definition.entity.css '3': name: punctuation.section.function.css '4': name: constant.language.css '5': name: punctuation.section.function.css - match: '((:)lang)\\s*(?:(\\()(\\w+(-\\w+)?)?(\\)))?' captures: '1': name: entity.other.attribute-name.pseudo-class.css '2': name: puncutation.definition.entity.css '3': name: punctuation.section.function.css '4': name: constant.language.css '6': name: punctuation.section.function.css - captures: '1': name: punctuation.definition.entity.css match: '(:)(active|hover|link|visited|focus)\\b' name: entity.other.attribute-name.pseudo-class.css - captures: '1': name: punctuation.definition.entity.css match: '(::)(shadow)\\b' name: entity.other.attribute-name.pseudo-class.css`; const subst = `$1$2$6$7\n$5$3$4`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result);

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