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

/
/
g

Test String

Code Generator

Language

Generated Code

const regex = /<a href="http.?:.*(youtube.com|.*be\/|.*embed\/|watch?. v=|(\w{11})).?<\/a>/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('<a href="http.?:.*(youtube.com|.*be\\\/|.*embed\\\/|watch?. v=|(\\w{11})).?<\\\/a>', 'g') const str = `the following URL will be found in a &lt;A&gt;:<br> <em> <a href="https://www.youtube.com/watch?t=61&amp;v=JozAmXo2bDE" rel="nofollow">https://www.youtube.com/watch?t=61&amp;v=JozAmXo2bDE</a> <br> <a href="https://soundcloud.com/buzzdeny/sets/deutsch-er-hiphop-rap" rel="nofollow">https://soundcloud.com/buzzdeny/sets/deutsch-er-hiphop-rap</a> <a href="https://www.youtube.com/watch?v=VH2QAMMSL40" rel="nofollow">https://www.youtube.com/watch?v=VH2QAMMSL40</a> <br> <a href="http://www.youtube.com/embed/NLqAF9hrVbY" rel="nofollow">http://www.youtube.com/embed/NLqAF9hrVbY</a> <br> <a href="http://youtu.be/NLqAF9hrVbY" rel="nofollow">http://youtu.be/NLqAF9hrVbY</a> </em> <br> <a href="http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/0/FJUvudQsKCM" rel="nofollow">http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/0/FJUvudQsKCM</a> </p> <a href="/uploads/files/1438381231924-humanistische-friedenspartei.mp3">Humanistische - Friedenspartei.mp3</a> <p>nice... <a href="/uploads/files/1438418374790-drumloop053_ambnt_160_x_sc5.wav">DRUMLOOP053_AMBNT_160_X_SC5.wav</a></p> <a href="/uploads/files/1438418374790-drumloop053_ambnt_160_x_sc5.wav">DRUMLOOP053_AMBNT_160_X_SC5.wav</a> <p>infos:<br> <a href="https://github.com/ogerly/nodebb-plugin-youtube-lite/blob/master/library.js" rel="nofollow">https://github.com/ogerly/nodebb-plugin-youtube-lite/blob/master/library.js</a> </p> <p><a href="https://github.com/ogerly/nodebb-plugin-youtube-lite" rel="nofollow">https://github.com/ogerly/nodebb-plugin-youtube-lite</a></p> </div>`; 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