Regular Expressions 101

Save & Share

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 = /^(["']?)(\$?([0-9]{1,3},([0-9]{3},?)*[0-9]{3}|[0-9]{1,3})((.[0-9]{0,3})[0-9]{0,10})?)\1$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(["\']?)(\\$?([0-9]{1,3},([0-9]{3},?)*[0-9]{3}|[0-9]{1,3})((.[0-9]{0,3})[0-9]{0,10})?)\\1$', 'gm') const str = `123456 123. . .123 123.154574 .545.4584 +1454 +487.54587 -54587.7487 .1225- .456+ 454.4+ 454.455874 45.45745687687.5678 45,547 45,5 ,154567891021 0,154567891021 123,1023458748 4546587,54587867 578,4 0 .123 0.00145 0.0 012345678910 1,345.154 4,330,234.34 5.545445454 3,023,123.34 12.1 5,356.12345678910 1.20 1.01 0.52 125.30 158,265.36 100,100,100,123,125,568,000.00 "" '' "1" '1' "123" '123' "123.1" '0' "123.12345647891" "19,741.24" 1234567891023154546574568768767866876767676876584764646546546465465464564564.240 "191741.240"`; // 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