Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

/
/
ig

Test String

Code Generator

Language

Generated Code

const regex = /(?<=watch\?v=|\/videos\/|embed\/|youtu.be\/|\/v\/|watch\?v%3D|%2Fvideos%2F|embed%2F|youtu.be%2F|%2Fv%2F)[^#\&\?\n]*/ig; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?<=watch\\?v=|\\\/videos\\\/|embed\\\/|youtu.be\\\/|\\\/v\\\/|watch\\?v%3D|%2Fvideos%2F|embed%2F|youtu.be%2F|%2Fv%2F)[^#\\&\\?\\n]*', 'ig') const str = `thisdoesnotmatch seulement11 l_la5XiQJdk http://www.youtube.com/watch?v=vpiMAaPTze8 http://youtu.be/l_la5XiQJdk http://youtu.be/NLqAF9hrVbY https://youtu.be/qT47KF5pvfw https://youtu.be/zImHyTyYhM8?t=4s http://www.youtube.com/v/NLqAF9hrVbY?fs=1&hl=en_US http://www.youtube.com/v/NLqAF9hrVbY?fs=1&hl=en_US http://www.youtube.com/watch?v=NLqAF9hrVbY http://www.youtube.com/user/Scobleizer#p/u/1/1p3vcRhsYGo http://www.youtube.com/ytscreeningroom?v=NRHVzbJVx8I http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/2/PPS-8DMrAn4 http://gdata.youtube.com/feeds/api/videos/NLqAF9hrVbY http://www.youtube.com/watch?v=spDj54kf-vY&feature=g-vrec http://www.youtube.com/watch?v=spDj54kf-vY&feature=youtu.be http://www.youtube-nocookie.com/watch?v=NLqAF9hrVbY http://www.youtube.com/embed/NLqAF9hrVbY https://www.youtube.com/embed/NLqAF9hrVbY https://www.youtube.com/watch?v=MRl7cxSOXdU&feature=youtu.be https://www.youtube.com/watch?v=q07SQFmL4rM https://www.youtube.com/watch?v=q07SQFmL4yM https://www.youtube.com/watch?time_continue=4&v=zImHyTyYhM8 http://www.youtube.com/embed/dQw4w9WgXcQ ... http://www.youtube.com/watch?v=dQw4w9WgXcQ ... http://www.youtube.com/?v=dQw4w9WgXcQ ... http://www.youtube.com/v/dQw4w9WgXcQ ... http://www.youtube.com/e/dQw4w9WgXcQ ... http://www.youtube.com/user/username#p/u/11/dQw4w9WgXcQ ... http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/0/dQw4w9WgXcQ ... http://www.youtube.com/watch?feature=player_embedded&v=dQw4w9WgXcQ ... http://www.youtube.com/?feature=player_embedded&v=dQw4w9WgXcQ ... https://www.youtube.com/watch?v=DFYRQ_zQ-gk&feature=featured https://www.youtube.com/watch?v=DFYRQ_zQ-gk http://www.youtube.com/watch?v=DFYRQ_zQ-gk //www.youtube.com/watch?v=DFYRQ_zQ-gk www.youtube.com/watch?v=DFYRQ_zQ-gk https://youtube.com/watch?v=DFYRQ_zQ-gk http://youtube.com/watch?v=DFYRQ_zQ-gk //youtube.com/watch?v=DFYRQ_zQ-gk youtube.com/watch?v=DFYRQ_zQ-gk https://m.youtube.com/watch?v=DFYRQ_zQ-gk http://m.youtube.com/watch?v=DFYRQ_zQ-gk //m.youtube.com/watch?v=DFYRQ_zQ-gk m.youtube.com/watch?v=DFYRQ_zQ-gk https://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US http://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US //www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US https://www.youtube.com/embed/DFYRQ_zQ-gk?autoplay=1 https://www.youtube.com/embed/DFYRQ_zQ-gk http://www.youtube.com/embed/DFYRQ_zQ-gk //www.youtube.com/embed/DFYRQ_zQ-gk www.youtube.com/embed/DFYRQ_zQ-gk https://youtube.com/embed/DFYRQ_zQ-gk http://youtube.com/embed/DFYRQ_zQ-gk //youtube.com/embed/DFYRQ_zQ-gk youtube.com/embed/DFYRQ_zQ-gk https://youtu.be/DFYRQ_zQ-gk?t=120 https://youtu.be/DFYRQ_zQ-gk http://youtu.be/DFYRQ_zQ-gk //youtu.be/DFYRQ_zQ-gk youtu.be/DFYRQ_zQ-gk https://www.youtube.com/watch?v=DFYRQ_zQ-gk&feature=featured https://www.youtube.com/watch?v=DFYRQ_zQ-gk http://www.youtube.com/watch?v=DFYRQ_zQ-gk //www.youtube.com/watch?v=DFYRQ_zQ-gk www.youtube.com/watch?v=DFYRQ_zQ-gk https://youtube.com/watch?v=DFYRQ_zQ-gk http://youtube.com/watch?v=DFYRQ_zQ-gk //youtube.com/watch?v=DFYRQ_zQ-gk youtube.com/watch?v=DFYRQ_zQ-gk https://m.youtube.com/watch?v=DFYRQ_zQ-gk http://m.youtube.com/watch?v=DFYRQ_zQ-gk //m.youtube.com/watch?v=DFYRQ_zQ-gk m.youtube.com/watch?v=DFYRQ_zQ-gk https://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US http://www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US //www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US www.youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US youtube.com/v/DFYRQ_zQ-gk?fs=1&hl=en_US https://www.youtube.com/embed/DFYRQ_zQ-gk?autoplay=1 https://www.youtube.com/embed/DFYRQ_zQ-gk http://www.youtube.com/embed/DFYRQ_zQ-gk //www.youtube.com/embed/DFYRQ_zQ-gk www.youtube.com/embed/DFYRQ_zQ-gk https://youtube.com/embed/DFYRQ_zQ-gk http://youtube.com/embed/DFYRQ_zQ-gk //youtube.com/embed/DFYRQ_zQ-gk youtube.com/embed/DFYRQ_zQ-gk https://youtu.be/DFYRQ_zQ-gk?t=120 https://youtu.be/DFYRQ_zQ-gk http://youtu.be/DFYRQ_zQ-gk //youtu.be/DFYRQ_zQ-gk youtu.be/DFYRQ_zQ-gk https://www.youtube.com/HamdiKickProduction?v=DFYRQ_zQ-gk `; // 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