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 = /(?<date>\d+\-\d+\-\d+).(?<time>\d+:\d+:\d+).(?<timetaken>\d+).(?<cip>\d+\.\d+\.\d+\.\d+).(?<scstatus>\d+).(?<scaction>\S+).(?<scbytes>\d+).(?<csbytes>\d+).(?<csmethod>\S+).(?<csurischeme>\S+).(?<cshost>\S+).(?<csuriport>\d+).(?<csuripath>\S+).(?<csuriquery>\S+).(?<csusername>\S+).(?<csauthgroup>\S+).(?<shierarchy>\S+).(?<ssuppliername>\S+).(?<rscontenttype>\S+).(?<csreferer>\S+)."?(?<cs_user_agent>.+)"?./gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?<date>\\d+\\-\\d+\\-\\d+).(?<time>\\d+:\\d+:\\d+).(?<timetaken>\\d+).(?<cip>\\d+\\.\\d+\\.\\d+\\.\\d+).(?<scstatus>\\d+).(?<scaction>\\S+).(?<scbytes>\\d+).(?<csbytes>\\d+).(?<csmethod>\\S+).(?<csurischeme>\\S+).(?<cshost>\\S+).(?<csuriport>\\d+).(?<csuripath>\\S+).(?<csuriquery>\\S+).(?<csusername>\\S+).(?<csauthgroup>\\S+).(?<shierarchy>\\S+).(?<ssuppliername>\\S+).(?<rscontenttype>\\S+).(?<csreferer>\\S+)."?(?<cs_user_agent>.+)"?.', 'gm') const str = `2014-03-27 12:39:32 20 10.71.15.207 304 TCP_HIT 367 1470 GET http www.computerworld.com 80 /elqNow/elqFCS.js - - - - 23.196.74.53 application/x-javascript http://www.computerworld.com/s/article/9247206/Gameover_malware_takes_aim_at_Monster.com_and_CareerBuilder.com "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)" OBSERVED "Technology/Internet" - 163.252.254.201 23.44.202.53 52809 `; // 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