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

/
/
mg

Test String

Code Generator

Generated Code

const regex = /(var preferences = {)[\s\S]*(};)/mg; // Alternative syntax using RegExp constructor // const regex = new RegExp('(var preferences = {)[\\s\\S]*(};)', 'mg') const str = `<!DOCTYPE html> <html> <head> <meta http-equiv='x-ua-compatible' content='IE=edge,chrome=1' /> <meta name="robots" content="nofollow" /> <meta name="robots" content="noindex" /> <meta name="robots" content="noarchive" /> <meta http-equiv="Cache-Control" content="private, no-cache, no-store, must-revalidate, max-age=0" /> <meta http-equiv="Pragma" content="no-cache" /> <meta http-equiv="Expires" content="0" /> <meta http-equiv="Expires" content="Tue, 01 Jan 1980 1:00:00 GMT" /> <meta charset='UTF-8' /> <title>BLANK - FILL WITH CLIENT TITLE</title> <link href='css/bpdev.css' rel='stylesheet' type='text/css' /> <script src='https://code.jquery.com/jquery-1.11.1.min.js'></script> <script>!window.jQuery && document.write('<script src="common/js/jquery/jquery-1.11.1.min.js"><\\/script>');</script> <link rel='shortcut icon' href='images/favicon.ico' type='image/x-icon' /> <style id="antiClickjack">body{display:none !important;}</style> </head> <body id='userTools'> <div id='notificationContainer' data-automation='notification_window'></div> <div id='overlay' class='modalOverlay' data-automation='modal_overlay'></div> <div id='dialog' class='modal' data-automation='modal_window'></div> <div id='container'> <div id='header' data-automation='header'></div> <div id='loader' data-automation='content_loader'></div> <div id='content' data-automation='content_area'></div> </div> <div id='copyFooter' class='copyright' data-automation='copyright_footer'></div> <script src='common/js/gateway.framework-min.js' type='text/javascript'></script> <script src='common/js/gateway.app-min.js' type='text/javascript'></script> <script type='text/javascript'> if (self === top) { var antiClickjack = document.getElementById('antiClickjack'); antiClickjack.parentNode.removeChild(antiClickjack); } else { top.location = self.location; } (function(\$) { var preferences = { logo : 'images/logo.png', logoWidth : 250, logoHeight : 38, logoAlt : '', logoLink : '', logoutURL : '../../pkmslogout' }; Gateway.startGateway(preferences, true); }(jQuery)); </script> </body> </html>`; // 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