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 = /--([a-z\d]+)-A--[\s\S]+?--\1-Z--/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('--([a-z\\d]+)-A--[\\s\\S]+?--\\1-Z--', 'gm') const str = `--f15a0000-A-- [30/Aug/2018:14:06:33 +0200] W4fdyYHC0Xb8YDuIqk5YQgAAAD0 127.0.0.1 55454 127.0.0.1 80 --f15a0000-B-- GET /FormValidation/page1.php HTTP/1.1 Host: localhost Connection: keep-alive Upgrade-Insecure-Requests: 1 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8 Referer: http://localhost/FormValidation/ Accept-Encoding: gzip, deflate, br Accept-Language: en-US,en;q=0.9 tanuser: 00198343 --f15a0000-F-- HTTP/1.1 200 OK X-Powered-By: PHP/5.6.35 Content-Length: 851 Keep-Alive: timeout=5, max=99 Connection: Keep-Alive Content-Type: text/html; charset=UTF-8 --f15a0000-Z-- --bb410000-A-- [30/Aug/2018:14:06:37 +0200] W4fdzYHC0Xb8YDuIqk5YQwAAAD0 127.0.0.1 55454 127.0.0.1 80 --bb410000-B-- POST /FormValidation/validation.php HTTP/1.1 Host: localhost Connection: keep-alive Content-Length: 33 Accept: */* Origin: http://localhost X-Requested-With: XMLHttpRequest User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36 Content-Type: application/x-www-form-urlencoded; charset=UTF-8 Referer: http://localhost/FormValidation/page1.php Accept-Encoding: gzip, deflate, br Accept-Language: en-US,en;q=0.9 tanuser: 00198343 --bb410000-C-- name1=test&email1=ssn%40gmail.com --bb410000-F-- HTTP/1.1 200 OK X-Powered-By: PHP/5.6.35 Content-Length: 17 Keep-Alive: timeout=5, max=98 Connection: Keep-Alive Content-Type: text/html; charset=UTF-8 --bb410000-Z--`; // 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