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

/
/

Test String

Code Generator

Language

Generated Code

const regex = /<script(?:\s+(?>"[\S\s]*?"|'[\S\s]*?'|(?:(?!\/>)[^>])?)+)?\s*>[\S\s]*?http:\/\/cdn\.walkme\.com\/users[\S\s]*?<\/script\s*(?=>)>/; // Alternative syntax using RegExp constructor // const regex = new RegExp('<script(?:\\s+(?>"[\\S\\s]*?"|\'[\\S\\s]*?\'|(?:(?!\\\/>)[^>])?)+)?\\s*>[\\S\\s]*?http:\\\/\\\/cdn\\.walkme\\.com\\\/users[\\S\\s]*?<\\\/script\\s*(?=>)>', '') const str = `<!DOCTYPE html> <html lang="en" dir="ltr" class="client-nojs"> <head> <meta charset="UTF-8" /> <title>International English Language Testing System - Wikipedia, the free encyclopedia</title> <meta name="generator" content="MediaWiki 1.25wmf2" /> <script type="text/javascript">(function() {var walkme = document.createElement('script'); walkme.type = 'text/javascript'; walkme.async = true; walkme.src='http://cdn.walkme.com/users/cb643dab0d6f4c7cbc9d436e7c06f719/walkme_cb643dab0d6f4c7cbc9d436e7c06f719.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(walkme, s); window._walkmeConfig = {smartLoad:true}; })();</script> <link rel="alternate" href="android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/International_English_Language_Testing_System" /> <link rel="alternate" type="application/x-wiki" title="Edit this page" href="/w/index.php?title=International_English_Language_Testing_System&amp;action=edit" /> `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; if ((m = regex.exec(str)) !== null) { // 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