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

r"
"
igm

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('^((gir *0aa)|((((?![qvx])[a-z][a-hk-y]?[0-9][0-9]?)|(((?![qvx])[a-z][0-9][a-hjkstuw])|((?![qvx])[a-z][a-hk-y][0-9][abehmnprvwxy]))) *([0-9](?![cikmov])[a-z]{2}))|(((?![qvx])[a-z][a-hk-y]?[0-9][0-9]?)|((?![qvx])[a-z][0-9][a-hjkstuw])|((?![qvx])[a-z][a-hk-y][0-9][abehmnprvwxy])))$', 'igm') const str = `GIR 0AA W1 6LS N1C 4UQ N17 6LA SW8 1UQ CW3 9SS SE5 0EG WC2H 7LT WC1N 2PL HU12 0AR N1C4UQ N176LA SW81UQ CW39SS SE50EG WC2H7LT WC1N2PL HU120AR W1 N1C N17 SW8 CW3 SE5 WC2H WC1N HU12 QA12 AJ12 Q1A A1V QA1N AZ1N AB1Z`; // 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