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

/
/

Test String

Code Generator

Language

Generated Code

const regex = /(?<req_ip>[\d\.]+)\s(?<req_unk1>[\w\-]+)\s(?<req_unk2>[\w\-]+)\s\[(?<req_ts>\d+\/\w+\/\d+\:\d+\:\d+\:\d+\s\+\d+)\]\s\"(?<req_full>.+?)\"\s(?<req_status>[\d\-]+)\s(?<req_bytes_in>[\d\-]+)\s\"(?<req_referrer>.+?)\"\s\"(?<req_ua>.+?)\"\s\"(?<req_cookie>.+?)\"\s\"(?<req_waf_info>.+?)\"\s\"(?<req_customfield>.+?)\"/; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?<req_ip>[\\d\\.]+)\\s(?<req_unk1>[\\w\\-]+)\\s(?<req_unk2>[\\w\\-]+)\\s\\[(?<req_ts>\\d+\\\/\\w+\\\/\\d+\\:\\d+\\:\\d+\\:\\d+\\s\\+\\d+)\\]\\s\\"(?<req_full>.+?)\\"\\s(?<req_status>[\\d\\-]+)\\s(?<req_bytes_in>[\\d\\-]+)\\s\\"(?<req_referrer>.+?)\\"\\s\\"(?<req_ua>.+?)\\"\\s\\"(?<req_cookie>.+?)\\"\\s\\"(?<req_waf_info>.+?)\\"\\s\\"(?<req_customfield>.+?)\\"', '') const str = `1.1.1.1 - - [05/May/2015:13:23:13 +0000] "HEAD /www.arl.com/path/to/file.php HTTP/1.1" 200 265 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" "-" "-" "UNKNOWN"`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; if ((m = regex.exec(str)) !== null) { // 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