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.:, ]+)) - (?<remote_user>\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<remote_ip>[\da-f.:]+)" (?:\-|(?P<upstream_response_time>\d+(?:.\d+)?))\s+(?P<request_time>\d+(?:.\d+)?) (?P<pipe>[\.p])/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:-|(?P<real_ip>[\\-\\da-f.:, ]+)) - (?<remote_user>\\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<remote_ip>[\\da-f.:]+)" (?:\\-|(?P<upstream_response_time>\\d+(?:.\\d+)?))\\s+(?P<request_time>\\d+(?:.\\d+)?) (?P<pipe>[\\.p])', 'gm') const str = `10.100.7.118 - - [02/Aug/2022:19:27:57 +0800] "GET /api/article/list/news HTTP/1.1" 200 103594 "https://165.npa.gov.tw/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/103.0.0.0 Safari/537.36" "172.27.31.231" 0.062 0.062 . 49.216.25.168, 203.66.34.45 - - [02/Aug/2022:19:28:10 +0800] "GET /assets/i18n/zh-tw.json HTTP/1.1" 200 9760 "https://165.npa.gov.tw/" "Mozilla/5.0 (iPhone; CPU iPhone OS 15_6 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/15E148" "172.27.31.231" 0.031 0.031 . `; // 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