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<real_ip>[\-\da-f.:]+))\s+\[(?P<remote_ip>[\da-f.:]+)\]\s+[\w\.\-]+\s+(?<remote_user>\S+)\s+\[(?<timestamp>[^\]]+)\]\s+"(?:\-|(?<request>\w+) (?<request_uri>[^ \?]+)(?:\?(?<request_uri_query>[^ ]*))? (?<request_version>[\w\/\.]+))"\s+(?P<status>[1-9]\d{2})\s+(?P<body_bytes_sent>\d+)\s+"(?<http_referer>[^"]+)"\s+"(?<http_user_agent>[^"]+)"\s+\[(?:\-|(?P<upstream_response_time>\d+(?:.\d+)?))\s+(?P<request_time>\d+(?:.\d+)?)\]/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:-|(?P<real_ip>[\\-\\da-f.:]+))\\s+\\[(?P<remote_ip>[\\da-f.:]+)\\]\\s+[\\w\\.\\-]+\\s+(?<remote_user>\\S+)\\s+\\[(?<timestamp>[^\\]]+)\\]\\s+"(?:\\-|(?<request>\\w+) (?<request_uri>[^ \\?]+)(?:\\?(?<request_uri_query>[^ ]*))? (?<request_version>[\\w\\\/\\.]+))"\\s+(?P<status>[1-9]\\d{2})\\s+(?P<body_bytes_sent>\\d+)\\s+"(?<http_referer>[^"]+)"\\s+"(?<http_user_agent>[^"]+)"\\s+\\[(?:\\-|(?P<upstream_response_time>\\d+(?:.\\d+)?))\\s+(?P<request_time>\\d+(?:.\\d+)?)\\]', 'gm') const str = `0.0.0.0 [192.168.255.53] - - [11/Aug/2020:06:25:22 +0000] "GET /monitoring/health/ HTTP/1.1" 200 0 "-" "-" [0.000 0.005] - [192.168.255.53] - - [11/Aug/2020:06:25:22 +0000] "GET /monitoring/health/ HTTP/1.1" 200 0 "-" "-" [0.000 0.005]`; // 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