Regular Expressions 101

Save & Manage Regex

  • Current Version: 2
  • 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
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 = /(?=.*(?:epub|digital|e-?(?:ISBN|book))).*ISBN(?: *13)?:?\s+\K(\d(?:-?\d){12})/gmi; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?=.*(?:epub|digital|e-?(?:ISBN|book))).*ISBN(?: *13)?:?\\s+\\K(\\d(?:-?\\d){12})', 'gmi') const str = `These should match to indicate they are eBook ISBNs: ISBN 978-1-9821-8584-8 (ebook) EISBN: 9781101487280 eISBN: 978-1-4406-3132-0 eISBN 9781429902304 Ebook ISBN: 9780593547342 eBook ISBN: 9780804139038 e-ISBN 978-0-765-37686-2 Digital Edition MAY 2017 ISBN: 978-0-06-244198-0 ISBN 13: 978-0-9999999-9-9 (eBook edition) EPub © Edition JUNE 2003 ISBN: 9780061739200 But then these should not match, as they are assumbed to be print copy ISBNs: Print ISBN: 978-0-06-244197-3 ISBN 978-1-9821-8582-4 ISBN 9780804139021 ISBN-13: 978-1-4299-6030-4 ISBN 13: 978-0-9999999-9-9 (Paperback edition)`; // 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