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
Processing...

Test String

Code Generator

Language

Generated Code

const regex = /^ (?:4[0-9]{12}(?:[0-9]{3})? | 5[1-5][0-9]{14} | 6(?:011|5[0-9][0-9])[0-9]{12} | 3[47][0-9]{13} | 3(?:0[0-5]|[68][0-9])[0-9]{11} | (?:2100|2131|1800|35\d{3})\d{11}) $/gmi; // Alternative syntax using RegExp constructor // const regex = new RegExp('^ (?:4[0-9]{12}(?:[0-9]{3})? | 5[1-5][0-9]{14} | 6(?:011|5[0-9][0-9])[0-9]{12} | 3[47][0-9]{13} | 3(?:0[0-5]|[68][0-9])[0-9]{11} | (?:2100|2131|1800|35\\d{3})\\d{11}) $', 'gmi') const str = `#American Express 370517943574132 372714451742486 370010255141385 341263547614307 343874494387669 #VISA 4024007125780444 4439944519233615 4658355677043536 4532926168018906 4532249806735728 #MasterCard 5524097521691644 5367170623993901 5553103980950937 5549194987582424 5141794881796756 #JCB 15 digits 180078244412845 210013400722277 210082510016250 180056142071970 210043823226606 #JCB 3158822586903214 3088687202983378 3158899851849561 3096803356450490 3337852908456769 #Dinners Club 30193567772121 30131361923813 30198560976769 30260244203356 36297440059376 `; // 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