Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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 = /(?m)^.*(?:(?:201[8-9]|2\d[2-9]\d|[3-9]\d{3})-\d{2}-\d{2}|2017-(?:12-\d{2}|11-(?:0[6-9]|[12]\d|3[01])))$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?m)^.*(?:(?:201[8-9]|2\\d[2-9]\\d|[3-9]\\d{3})-\\d{2}-\\d{2}|2017-(?:12-\\d{2}|11-(?:0[6-9]|[12]\\d|3[01])))$', 'gm') const str = `drwxrwxr-x - testetl hdp_test 0 2018-02-02 05:10 /raw/ADS/ClicksData/click/datetm=2017-10-15 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:35 /raw/ADS/ClicksData/click/datetm=2017-10-16 drwxrwxr-x - testetl hdp_test 0 2018-01-31 21:54 /raw/ADS/ClicksData/click/datetm=2017-10-17 drwxrwxr-x - testetl hdp_test 0 2018-01-31 23:59 /raw/ADS/ClicksData/click/datetm=2017-10-18 drwxrwxr-x - testetl hdp_test 0 2018-01-31 21:49 /raw/ADS/ClicksData/click/datetm=2017-10-19 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:32 /raw/ADS/ClicksData/click/datetm=2017-10-20 drwxrwxr-x - testetl hdp_test 0 2018-02-02 11:51 /raw/ADS/ClicksData/click/datetm=2017-10-21 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:08 /raw/ADS/ClicksData/click/datetm=2017-10-22 drwxrwxr-x - testetl hdp_test 0 2018-01-31 22:42 /raw/ADS/ClicksData/click/datetm=2017-10-23 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:58 /raw/ADS/ClicksData/click/datetm=2017-10-24 drwxrwxr-x - testetl hdp_test 0 2018-02-02 05:10 /raw/ADS/ClicksData/click/datetm=2017-10-25 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:46 /raw/ADS/ClicksData/click/datetm=2017-10-26 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:04 /raw/ADS/ClicksData/click/datetm=2017-10-27 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:46 /raw/ADS/ClicksData/click/datetm=2017-10-28 drwxrwxr-x - testetl hdp_test 0 2018-02-02 00:21 /raw/ADS/ClicksData/click/datetm=2017-10-29 drwxrwxr-x - testetl hdp_test 0 2018-02-02 05:09 /raw/ADS/ClicksData/click/datetm=2017-10-30 drwxrwxr-x - testetl hdp_test 0 2018-02-02 05:13 /raw/ADS/ClicksData/click/datetm=2017-10-31 drwxrwxr-x - testetl hdp_test 0 2018-02-01 14:34 /raw/ADS/ClicksData/click/datetm=2017-11-01 drwxrwxr-x - testetl hdp_test 0 2018-02-02 09:20 /raw/ADS/ClicksData/click/datetm=2017-11-02 drwxrwxr-x - testetl hdp_test 0 2018-02-01 14:35 /raw/ADS/ClicksData/click/datetm=2017-11-03 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:42 /raw/ADS/ClicksData/click/datetm=2017-11-04 drwxrwxr-x - testetl hdp_test 0 2018-02-02 09:18 /raw/ADS/ClicksData/click/datetm=2017-11-05 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:11 /raw/ADS/ClicksData/click/datetm=2017-11-06 drwxrwxr-x - testetl hdp_test 0 2018-01-31 17:56 /raw/ADS/ClicksData/click/datetm=2017-11-07 drwxrwxr-x - testetl hdp_test 0 2018-01-31 21:36 /raw/ADS/ClicksData/click/datetm=2017-11-08 drwxrwxr-x - testetl hdp_test 0 2018-01-31 16:43 /raw/ADS/ClicksData/click/datetm=2017-11-09 drwxrwxr-x - testetl hdp_test 0 2018-01-31 21:59 /raw/ADS/ClicksData/click/datetm=2017-11-10 drwxrwxr-x - testetl hdp_test 0 2018-02-01 09:23 /raw/ADS/ClicksData/click/datetm=2017-11-11 `; // 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