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

Generated Code

const regex = /^N/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^N', 'gm') const str = `Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras vitae diam venenatis, aliquet risus eget, pretium mi. Pellentesque vel turpis eget massa lacinia feugiat. Aenean dolor nibh, porttitor quis eros sed, blandit malesuada orci. Proin quis ipsum at felis suscipit fermentum in in tellus. Vivamus vel vulputate metus. Ut eget molestie metus. Proin quis elit non augue egestas aliquet vel sit amet dolor. Sed tincidunt eros at imperdiet viverra. Praesent imperdiet augue nec elementum pulvinar. Nam auctor vel libero eu hendrerit. Donec urna lectus, bibendum vel turpis in, dapibus faucibus ante. Mauris quam dui, ultrices in elit elementum, semper accumsan dolor. Nullam rutrum nisl libero, in elementum lectus suscipit sit amet. Nullam varius magna leo, ut blandit elit rhoncus vitae. Nam fringilla congue urna id feugiat. Etiam a tortor luctus, porttitor nulla sit amet, luctus sem. Praesent eleifend, quam ac porta pharetra, mauris felis sollicitudin nibh, et varius mi magna eu arcu. Morbi a dui sem. Donec convallis nibh lorem, sed venenatis enim eleifend ut. Phasellus et semper nisl.`; // 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