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

/
/
gmui

Test String

Code Generator

Language

Generated Code

const regex = /(?:[^\p{Script=Latin}\s\w;:.,\-[\](){}'"+\/=<>])\B|(?:(?:[\p{Script=Latin}]|[^\s\w;:.,\-[\](){}'"+\/=<>]){2,}(?:(?:[\p{Script=Latin}]|[^\s\w+.,–:;\/\\=<>])?(?:[\p{Script=Latin}]|[^\s\w;\-:.,\[\](){}'"+\/\\=<>]))*)|(?:(?:[0-9\p{Script=Latin}]|[^\s\w;:.,[\](){}\-'"+\/\\=<>])(?:(?:[0-9\p{Script=Latin}]|[^\s\w+\-:;\/\\=<>])?(?:[0-9\p{Script=Latin}]|[^\s\w;:.,\-[\](){}'"+\/\\=<>]))*)/gmui; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:[^\\p{Script=Latin}\\s\\w;:.,\\-[\\](){}\'"+\\\/=<>])\\B|(?:(?:[\\p{Script=Latin}]|[^\\s\\w;:.,\\-[\\](){}\'"+\\\/=<>]){2,}(?:(?:[\\p{Script=Latin}]|[^\\s\\w+.,–:;\\\/\\\\=<>])?(?:[\\p{Script=Latin}]|[^\\s\\w;\\-:.,\\[\\](){}\'"+\\\/\\\\=<>]))*)|(?:(?:[0-9\\p{Script=Latin}]|[^\\s\\w;:.,[\\](){}\\-\'"+\\\/\\\\=<>])(?:(?:[0-9\\p{Script=Latin}]|[^\\s\\w+\\-:;\\\/\\\\=<>])?(?:[0-9\\p{Script=Latin}]|[^\\s\\w;:.,\\-[\\](){}\'"+\\\/\\\\=<>]))*)', 'gmui') const str = `Bão Yagi (được Việt Nam định danh là bão số 3, được phía Philippines đặt tên bão Enteng - tiếng Anh: Severe Tropical Storm Enteng , nguyên văn 'Bão nhiệt đới dữ dội Enteng') Some legal "[d]ocuments" contain corrected spel[l]ing, gram(m)ar, or simple typos; and lots of references[1]. By Extension, I included curl{e}y brackets, but not tag brack<e>ts, which are not seenin modern legal documents. These.are.properly.separated.even.U.S.A., and multiple punctuations are properly ignored. A. Multiple B. Choices -ABC-DEF- -A-B-C-D- -1-2-3-4- -test- .ABC.DEF. .AB.CD.EF.D. .A.B.C.D.E. .123.456.789. .12.34.56.78. .1.2.3.4. cod3 var1aBl3s test.U.S.A.test We'd want hyphenated words in cases when large words are broken for wrapping in tight column news papers/megazines, while we can still properly separate numbers such as "30-35 pages". Non-Latin character are separated per character: 出典: フリー百科事典『ウィキペディア（Wikipedia）』 ウィキペディアには現在この名前の項目はありません。 Acceptable failed cases: - [E]xpected: "[" is considered external "wrapper/enclosure", while the internal "wrappers" are included so that they can be further processed/removed in the future. - test.U.S.A.test: this happens when no space trailing textContents of a block-level elemetn in HTML files. - 『ウィキペディア（Wikipedia）』: mixed languages - CamelCasing s not separated, but can be easily separated in "post-processing step, even though _snake_casing_ works fine by happenstance. -cod3 var1aBl3s: mixing letters and numbers. It's not intentional, but not a big deal when the side-effect is new word is always started with a number.`; // 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