Regular Expressions 101

Save & Manage Regex

  • Current Version: 1
  • Save & Share
  • Community Library

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
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
Processing...

Test String

Code Generator

Language

Generated Code

const regex = /\b(?:(?:31(\/|-| |\.)(?:0?[13578]|1[02]|(?:Jan|January|Mar|March|May|Jul|July|Aug|August|Oct|October|Dec|December)))\1|(?:(?:29|30)(\/|-| |\.)(?:0?[1,3-9]|1[0-2]|(?:Jan|January|Mar|March|Apr|April|May|Jun|June|Jul|July|Aug|August|Sep|September|Oct|October|Nov|November|Dec|December))\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})\b|\b(?:29(\/|-| |\.)(?:0?2|(?:Feb|February))\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))\b|\b(?:0?[1-9]|1\d|2[0-8])(\/|-| |\.)(?:(?:0?[1-9]|(?:Jan|January|Feb|February|Mar|March|Apr|April|May|Jun|June|Jul|July|Aug|August|Sep|September))|(?:1[0-2]|(?:Oct|October|Nov|November|Dec|December)))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})\b/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('\\b(?:(?:31(\\\/|-| |\\.)(?:0?[13578]|1[02]|(?:Jan|January|Mar|March|May|Jul|July|Aug|August|Oct|October|Dec|December)))\\1|(?:(?:29|30)(\\\/|-| |\\.)(?:0?[1,3-9]|1[0-2]|(?:Jan|January|Mar|March|Apr|April|May|Jun|June|Jul|July|Aug|August|Sep|September|Oct|October|Nov|November|Dec|December))\\2))(?:(?:1[6-9]|[2-9]\\d)?\\d{2})\\b|\\b(?:29(\\\/|-| |\\.)(?:0?2|(?:Feb|February))\\3(?:(?:(?:1[6-9]|[2-9]\\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))\\b|\\b(?:0?[1-9]|1\\d|2[0-8])(\\\/|-| |\\.)(?:(?:0?[1-9]|(?:Jan|January|Feb|February|Mar|March|Apr|April|May|Jun|June|Jul|July|Aug|August|Sep|September))|(?:1[0-2]|(?:Oct|October|Nov|November|Dec|December)))\\4(?:(?:1[6-9]|[2-9]\\d)?\\d{2})\\b', 'gm') const str = `From 1 March 1960 To 1 March 2235 For a period starting 01/03/1960 and ending 01/03/2235 Starting 1.3.1960 and ending 1.3.2235 For a period starting 1/3/1960 and ending 1/3/2235 From 1 June 1960 To 1 July 2235 From 1-June-1960 To 1-July-2235 29-02-2008 29-Feb-2008 29-02-2009 29-Feb-2009 29/Feb/20 29-Feb-21 29-10-2008 31-12-2008 31-11-2008 `; // 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