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

/
/
g

Test String

Code Generator

Language

Generated Code

const regex = /href="([^"]+)"/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('href="([^"]+)"', 'g') const str = ` <!DOCTYPE html> <html lang="fr"> <head></head> <body> <div id="wm-ipp" class="" lang="en" style="display: block;"></div> <!-- BEGIN WAYBACK TOOLBAR INSERT --> <script src="/static/js/disclaim-element.js" type="text/javascript"></script> <script src="/static/js/graph-calc.js" type="text/javascript"></script> <script src="/static/jflot/jquery.min.js" type="text/javascript"></script> <script type="text/javascript"></script> <style type="text/css"></style> <script type="text/javascript"></script> <!-- END WAYBACK TOOLBAR INSERT --> <header id="main_header"> <div class="header_content"></div> </header> <div id="main_content"> <div id="under_top_event"></div> <div id="breadcrumbs"></div> <div id="main_search"></div> <div id="content"> <div id="page_test" class="home"> <div id="topline"> <h1> TESTS </h1> </div> <div class="large_column left_column"> <a class="top" title="Lire le test : The Final Fantasy" href="/web/20121023121603/http://www.gameweb.fr/articles/test-65-the-final-fantasy-3ds-page-opinion.html"></a> <div class="separation" style="margin: 20px 0;"></div> <a class="high" title="Lire le test : El Shaddai : Ascension of The Metatron" href="/web/20121023121603/http://www.gameweb.fr/articles/test-63-el-shaddai-ascension-of-the-metatron-ps3-page-opinion.html"></a> <a class="high" title="Lire le test : Heroes of Ruin" href="/web/20121023121603/http://www.gameweb.fr/articles/test-62-heroes-of-ruin-3ds-page-opinion.html"></a> <a class="high" title="Lire le test : Prototype 2" href="/web/20121023121603/http://www.gameweb.fr/articles/test-61-prototype-2-ps3-page-opinion.html"></a> <a class="high" title="Lire le test : Rayman Origins" href="/web/20121023121603/http://www.gameweb.fr/articles/test-60-rayman-origins-ps3-page-opinion.html"></a> </div> <div class="medium_column right_column" style="padding-top: 70px;"> <a class="medium" title="Lire le test : Mass Effect 3" href="/web/20121023121603/http://www.gameweb.fr/articles/test-59-mass-effect-3-x360-page-opinion.html"> <span class="small title"></span> <span class="put_score score"></span> <span class="description"></span> </a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Pandora's Tower" href="/web/20121023121603/http://www.gameweb.fr/articles/test-58-pandoras-tower-wii-page-opinion.html"> <span class="small title"></span> <span class="put_score score"></span> <span class="description"></span> </a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : I am alive" href="/web/20121023121603/http://www.gameweb.fr/articles/test-57-i-am-alive-x360-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Silent hill downpour" href="/web/20121023121603/http://www.gameweb.fr/articles/test-56-silent-hill-downpour-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Naruto Storm Generations" href="/web/20121023121603/http://www.gameweb.fr/articles/test-55-naruto-storm-generations-x360-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Street Fighter x Tekken" href="/web/20121023121603/http://www.gameweb.fr/articles/test-54-street-fighter-x-tekken-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Ninja Gaiden 3" href="/web/20121023121603/http://www.gameweb.fr/articles/test-53-ninja-gaiden-3-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Asura's Wrath" href="/web/20121023121603/http://www.gameweb.fr/articles/test-52-asuras-wrath-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : The Last Story" href="/web/20121023121603/http://www.gameweb.fr/articles/test-51-the-last-story-wii-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Xenoblade" href="/web/20121023121603/http://www.gameweb.fr/articles/test-50-xenoblade-wii-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : SSX" href="/web/20121023121603/http://www.gameweb.fr/articles/test-48-ssx-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Syndicate" href="/web/20121023121603/http://www.gameweb.fr/articles/test-47-syndicate-pc-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Resident Evil Revelations" href="/web/20121023121603/http://www.gameweb.fr/articles/test-46-resident-evil-revelations-3ds-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Binary Domain" href="/web/20121023121603/http://www.gameweb.fr/articles/test-45-binary-domain-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Catherine" href="/web/20121023121603/http://www.gameweb.fr/articles/test-43-catherine-x360-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> <a class="medium" title="Lire le test : Soulcalibur V" href="/web/20121023121603/http://www.gameweb.fr/articles/test-44-soulcalibur-v-ps3-page-opinion.html"></a> <div class="separation" style="margin: 10px 0;"></div> </div> </div> </div> </div> <footer id="main_footer"></footer> </body> </html> <!-- FILE ARCHIVED ON 12:16:03 oct. 23, 2012 AND … --> `; // 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