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

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /(?P<req_ip>^[\d\.]+)\s+(?P<req_identity>.+?)\s+(?P<req_user>.+?)\s+(?P<req_date>.+?)\s+(?P<req_offset>.+?)\s+"(?P<req_method>.+?)\s+(?P<req_path>.+?)\s+(?P<req_protocoll>.+?)"\s+(?P<req_code>.+?)\s+(?P<req_size>.+?)\s+"(?P<req_referer>.+?)"\s+"(?P<req_device>.+?)"/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?P<req_ip>^[\\d\\.]+)\\s+(?P<req_identity>.+?)\\s+(?P<req_user>.+?)\\s+(?P<req_date>.+?)\\s+(?P<req_offset>.+?)\\s+"(?P<req_method>.+?)\\s+(?P<req_path>.+?)\\s+(?P<req_protocoll>.+?)"\\s+(?P<req_code>.+?)\\s+(?P<req_size>.+?)\\s+"(?P<req_referer>.+?)"\\s+"(?P<req_device>.+?)"', 'gm') const str = `165.72.104.6 - admin 12/May/2021:09:37:52 +0000 "GET /etc/clientlibs/website/global/public/img/loading.gif HTTP/1.1" 200 17585 "https://my.domain.com/etc/clientlibs/website/global/public/stylesheets/project-base.108cb261dae9b1ccd0121c7571bbd42f2fc6d0a78a9bffb03b16be08753a32ad.css" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36"`; // 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