Regular Expressions 101

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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 = /(?xi)^( (AT)?U[0-9]{8} | # Austria (BE)?0[0-9]{9} | # Belgium (BG)?[0-9]{9,10} | # Bulgaria (HR)?[0-9]{11} | # Croatia (CY)?[0-9]{8}L | # Cyprus (CZ)?[0-9]{8,10} | # Czech Republic (DE)?[0-9]{9} | # Germany (DK)?[0-9]{8} | # Denmark (EE)?[0-9]{9} | # Estonia (EL|GR)?[0-9]{9} | # Greece ES[A-Z][0-9]{7}(?:[0-9]|[A-Z]) | # Spain (FI)?[0-9]{8} | # Finland (FR)?[0-9A-Z]{2}[0-9]{9} | # France (GB)?([0-9]{9}([0-9]{3})?|[A-Z]{2}[0-9]{3}) | # United Kingdom (HU)?[0-9]{8} | # Hungary (IE)?[0-9]S[0-9]{5}L | # Ireland (IT)?[0-9]{11} | # Italy (LT)?([0-9]{9}|[0-9]{12}) | # Lithuania (LU)?[0-9]{8} | # Luxembourg (LV)?[0-9]{11} | # Latvia (MT)?[0-9]{8} | # Malta (NL)?[0-9]{9}B[0-9]{2} | # Netherlands (PL)?[0-9]{10} | # Poland (PT)?[0-9]{9} | # Portugal (RO)?[0-9]{2,10} | # Romania (SE)?[0-9]{12} | # Sweden (SI)?[0-9]{8} | # Slovenia (SK)?[0-9]{10} # Slovakia )$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?xi)^( (AT)?U[0-9]{8} | # Austria (BE)?0[0-9]{9} | # Belgium (BG)?[0-9]{9,10} | # Bulgaria (HR)?[0-9]{11} | # Croatia (CY)?[0-9]{8}L | # Cyprus (CZ)?[0-9]{8,10} | # Czech Republic (DE)?[0-9]{9} | # Germany (DK)?[0-9]{8} | # Denmark (EE)?[0-9]{9} | # Estonia (EL|GR)?[0-9]{9} | # Greece ES[A-Z][0-9]{7}(?:[0-9]|[A-Z]) | # Spain (FI)?[0-9]{8} | # Finland (FR)?[0-9A-Z]{2}[0-9]{9} | # France (GB)?([0-9]{9}([0-9]{3})?|[A-Z]{2}[0-9]{3}) | # United Kingdom (HU)?[0-9]{8} | # Hungary (IE)?[0-9]S[0-9]{5}L | # Ireland (IT)?[0-9]{11} | # Italy (LT)?([0-9]{9}|[0-9]{12}) | # Lithuania (LU)?[0-9]{8} | # Luxembourg (LV)?[0-9]{11} | # Latvia (MT)?[0-9]{8} | # Malta (NL)?[0-9]{9}B[0-9]{2} | # Netherlands (PL)?[0-9]{10} | # Poland (PT)?[0-9]{9} | # Portugal (RO)?[0-9]{2,10} | # Romania (SE)?[0-9]{12} | # Sweden (SI)?[0-9]{8} | # Slovenia (SK)?[0-9]{10} # Slovakia )$', 'gm') const str = `ATU99999999 BE0999999999 BG999999999 HR12345678901 CY99999999L CZ12345678 DK99999999 EE123456789 FI99999999 FRXX999999999 DE999999999 EL123456789 HU12345678 IE1S23456L IE1234567T IE1234567TW IE1234567FA ESA12345678 ESZ1234567E`; // 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