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

/
/
gmx

Test String

Code Generator

Language

Generated Code

const regex = /(?(DEFINE) (?P<ver>\d+(?:\.\d+)*(?![.\d])) (?P<agent>Mozilla\/(?&ver)) (?P<os>(?&os_windows)|(?&os_linux)|(?&os_macintosh)|(?&os_ios)) (?P<os_windows>Windows[ ]\w+[ ](?&ver)) (?P<os_linux>Linux(?:[ ](?:i686|x86_64))?) (?P<os_macintosh>Macintosh) (?P<os_ios>(?:CPU[ ])?iPhone[ ]OS|CPU[ ]OS.*?like[ ]Mac[ ]OS[ ]X) (?P<device>(?&device_ios)|(?&device_firefox)|(?&device_android)) (?P<device_ios>iPhone|iPad) (?P<device_firefox>Mobile) (?P<device_android>Android(?:[ ](?&ver))?) (?P<browser> (?: (?&browser_ie) | (?&browser_safari) | (?&browser_chrome) | (?&browser_chromium) | (?&browser_firefox) | (?&browser_version) # | (?&browser_nexus) | (?&browser_mobile) | (?&browser_gsa) | (?&browser_quicklook) | (?&browser_opera) ) [ \/] (?: [A-Z\d]+\b(?!\.) | (?&ver) ) ) (?P<browser_safari>(?:Mobile[ ])?Safari) (?P<browser_chrome>Chrome) (?P<browser_chromium>\b\w+\b[ ]Chromium) (?P<browser_firefox>Firefox) (?P<browser_ie>MSIE) (?P<browser_version>Version) (?P<browser_nexus>Nexus[ ]\d+[ ]Build) (?P<browser_mobile>Mobile) (?P<browser_gsa>GSA) (?P<browser_quicklook>QuickLook) (?P<browser_opera>OPR) ) ^ (?:(?=.*?(?P<Agent>(?&agent)))) (?:(?=.*?(?P<OS>(?&os)))) (?:(?=.*?(?P<Device>(?&device))))? (?:(?=.*?(?P<Browser>(?&browser)(?:[ ](?&browser))*)))?/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?(DEFINE) (?P<ver>\\d+(?:\\.\\d+)*(?![.\\d])) (?P<agent>Mozilla\\\/(?&ver)) (?P<os>(?&os_windows)|(?&os_linux)|(?&os_macintosh)|(?&os_ios)) (?P<os_windows>Windows[ ]\\w+[ ](?&ver)) (?P<os_linux>Linux(?:[ ](?:i686|x86_64))?) (?P<os_macintosh>Macintosh) (?P<os_ios>(?:CPU[ ])?iPhone[ ]OS|CPU[ ]OS.*?like[ ]Mac[ ]OS[ ]X) (?P<device>(?&device_ios)|(?&device_firefox)|(?&device_android)) (?P<device_ios>iPhone|iPad) (?P<device_firefox>Mobile) (?P<device_android>Android(?:[ ](?&ver))?) (?P<browser> (?: (?&browser_ie) | (?&browser_safari) | (?&browser_chrome) | (?&browser_chromium) | (?&browser_firefox) | (?&browser_version) # | (?&browser_nexus) | (?&browser_mobile) | (?&browser_gsa) | (?&browser_quicklook) | (?&browser_opera) ) [ \\\/] (?: [A-Z\\d]+\\b(?!\\.) | (?&ver) ) ) (?P<browser_safari>(?:Mobile[ ])?Safari) (?P<browser_chrome>Chrome) (?P<browser_chromium>\\b\\w+\\b[ ]Chromium) (?P<browser_firefox>Firefox) (?P<browser_ie>MSIE) (?P<browser_version>Version) (?P<browser_nexus>Nexus[ ]\\d+[ ]Build) (?P<browser_mobile>Mobile) (?P<browser_gsa>GSA) (?P<browser_quicklook>QuickLook) (?P<browser_opera>OPR) ) ^ (?:(?=.*?(?P<Agent>(?&agent)))) (?:(?=.*?(?P<OS>(?&os)))) (?:(?=.*?(?P<Device>(?&device))))? (?:(?=.*?(?P<Browser>(?&browser)(?:[ ](?&browser))*)))?', 'gm') const str = ``; // 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