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<timestamp>[^\s]+)\s*(?P<elb>[^\s]+)\s*(?P<client_addr>[^:]+):\s*(?P<client_port>[^\s]+)\s*(?P<target_addr>[^:]+):\s*(?P<target_port>[^\s]+)\s*(?P<request_processing_time>[^\s]+)\s*(?P<backend_processing_time>[^\s]+)\s*(?P<response_processing_time>[^\s]+)\s*(?P<elb_status_code>[^\s]+)\s*(?P<backend_status_code>[^\s]+)\s*(?P<received_bytes>[^\s]+)\s*(?P<sent_bytes>[^\s]+)\s*"(?P<request>[^\"]+)"\s*(?P<user_agent>[^\s]+)\s*(?P<ssl_cipher>[^\s]+)\s*(?P<ssl_protocol>[^\s]+)/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?P<timestamp>[^\\s]+)\\s*(?P<elb>[^\\s]+)\\s*(?P<client_addr>[^:]+):\\s*(?P<client_port>[^\\s]+)\\s*(?P<target_addr>[^:]+):\\s*(?P<target_port>[^\\s]+)\\s*(?P<request_processing_time>[^\\s]+)\\s*(?P<backend_processing_time>[^\\s]+)\\s*(?P<response_processing_time>[^\\s]+)\\s*(?P<elb_status_code>[^\\s]+)\\s*(?P<backend_status_code>[^\\s]+)\\s*(?P<received_bytes>[^\\s]+)\\s*(?P<sent_bytes>[^\\s]+)\\s*"(?P<request>[^\\"]+)"\\s*(?P<user_agent>[^\\s]+)\\s*(?P<ssl_cipher>[^\\s]+)\\s*(?P<ssl_protocol>[^\\s]+)', 'gm') const str = `2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80 0.000086 0.001048 0.001337 200 200 0 57 "GET https://www.example.com:443/ HTTP/1.1" "curl/7.38.0" DHE-RSA-AES128-SHA TLSv1.2 2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80 0.001069 0.000028 0.000041 - - 82 305 "- - - " "-" - - 2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817 10.0.0.1:80 0.001065 0.000015 0.000023 - - 57 502 "- - - " "-" ECDHE-ECDSA-AES128-GCM-SHA256 TLSv1.2`; // 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