Regular Expressions 101

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Function

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  • Substitution
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  • Unit Tests (36)
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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
Processing...

Test String

Code Generator

Language

Generated Code

const regex = /^(?!.*\-\-)((main|next|staging|dev(elop)?|test(ing)?)$|^((feat(ure)?|(bug|hot)?fix|docs|wip|test(ing)?)\/(?!\-)([a-z0-9\-]{1,50}(?<!-)\/(?!\-))?[a-z0-9\-]{1,100}(?<!-))$|^release\/v?(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?)$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?!.*\\-\\-)((main|next|staging|dev(elop)?|test(ing)?)$|^((feat(ure)?|(bug|hot)?fix|docs|wip|test(ing)?)\\\/(?!\\-)([a-z0-9\\-]{1,50}(?<!-)\\\/(?!\\-))?[a-z0-9\\-]{1,100}(?<!-))$|^release\\\/v?(0|[1-9]\\d*)\\.(0|[1-9]\\d*)\\.(0|[1-9]\\d*)(?:-((?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\\.(?:0|[1-9]\\d*|\\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\\+([0-9a-zA-Z-]+(?:\\.[0-9a-zA-Z-]+)*))?)$', 'gm') const str = `main next staging dev develop test feat/lorem-ipsum feature/dolorm test/a-separate-branch-just-to-test-a-new-feature bugfix/182-this-and-that wip/work-in-progress-but-for-some-reason-someone-made-a-branch fix/correct-branch bugfix/517/alternative-bugfix-thingy docs/reference/this-is-just-on-the-verge-of-being-way-too-long-but-it-is-still-acceptable-as-its-under-a-hundred docs/reference/this-is-just-on-the-verge-of-being-way-too-long-but-it-is-still-acceptable-as-its-exactly-hundred-ch hotfix/cannot-end-with-a-dash- docs/no-consecutive-dashes release/v1.0.0 release/1.0.0 release/v1.0.0-alpha.12 release/5123.1.5-some-meta-data docs/gfdgdfs- release docs//no-consecutive-slashes dev/invalid wrong/im-wrong docs/Bad-Casing release/invalid_characters docs/reference/this-one-is-obviously-just-way-too-long-to-make-sense-or-to-be-at-all-considered-by-the-expression-to-be-correct-as-its-very-clearly-not-correct-at-all feat/cannot-end-with-a-slash/ docs/one/too/many/slashes`; // 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