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

/
/
isg

Test String

Code Generator

Language

Generated Code

const regex = /(<script\b[^><]*>)(.*?)(<\/script>)|\bon\w+\s*=\s*\K(?|(\")([^\"]+)\"|(')([^']+)')/isg; // Alternative syntax using RegExp constructor // const regex = new RegExp('(<script\\b[^><]*>)(.*?)(<\\\/script>)|\\bon\\w+\\s*=\\s*\\K(?|(\\")([^\\"]+)\\"|(\')([^\']+)\')', 'isg') const str = `<div id='content' onClick='abc()'>Lorem On='abc' ipsum on to</div> <input id='a' type='range'> <input id='b' type='range'> <script>abc();</script> Jan23: The following is an addition set of tests including escaping quotes and .replace(/'/ situations that can cause problems. <div id='content' onClick='yyy("ere\\'xyz\\'").value=\\'ewew\\'; yyy("jhrhej")' >Lorem On='abc' ipsum on to</div> <input id='a' type='range' onPress="xxx(document.getElementById(\\"abc\\"))" onSomething="yyy(\\'fehrje\\')" onSomethingElse="document.getElementById('content').innerHTML.replace(/"/g, \\"dq\\")"> <input id='b' type='range'> <script> function abc() {console.log('abc()');}; function xxx(elem) {console.log('xxx:'+elem.className);}; function yyy(str) {console.log('yyy:'+str);}; yyy("ere\\'xyz\\'"); yyy("jhrhej"); var aaa=document.getElementById('content').innerHTML; var bbb=document.getElementById('content').innerHTML; abc(); aaa.replace(/'/g, "single-quotes"); bbb.replace(/'/g, 'single-quotes'); aaa.replace(/"/g, "quotes"); bbb.replace(/"/g, 'quotes'); </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