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

/
/

Test String

Code Generator

Language

Generated Code

const regex = /^[A-Za-z][A-Za-z0-9+\-.]*:(?:\/\/(?:(?:[A-Za-z0-9\-._~!$&'()*+,;=:]|%[0-9A-Fa-f]{2})*@)?(?:\[(?:(?:(?:(?:[0-9A-Fa-f]{1,4}:){6}|::(?:[0-9A-Fa-f]{1,4}:){5}|(?:[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){4}|(?:(?:[0-9A-Fa-f]{1,4}:){0,1}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){3}|(?:(?:[0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){2}|(?:(?:[0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:|(?:(?:[0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::)(?:[0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))|(?:(?:[0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(?:(?:[0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::)|[Vv][0-9A-Fa-f]+\.[A-Za-z0-9\-._~!$&'()*+,;=:]+)\]|(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|(?:[A-Za-z0-9\-._~!$&'()*+,;=]|%[0-9A-Fa-f]{2})*)(?::[0-9]*)?(?:\/(?:[A-Za-z0-9\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*|\/(?:(?:[A-Za-z0-9\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})+(?:\/(?:[A-Za-z0-9\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*)?|(?:[A-Za-z0-9\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})+(?:\/(?:[A-Za-z0-9\-._~!$&'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*|)(?:\?(?:[A-Za-z0-9\-._~!$&'()*+,;=:@\/?]|%[0-9A-Fa-f]{2})*)?(?:\#(?:[A-Za-z0-9\-._~!$&'()*+,;=:@\/?]|%[0-9A-Fa-f]{2})*)?$/; // Alternative syntax using RegExp constructor // const regex = new RegExp('^[A-Za-z][A-Za-z0-9+\\-.]*:(?:\\\/\\\/(?:(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:]|%[0-9A-Fa-f]{2})*@)?(?:\\[(?:(?:(?:(?:[0-9A-Fa-f]{1,4}:){6}|::(?:[0-9A-Fa-f]{1,4}:){5}|(?:[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){4}|(?:(?:[0-9A-Fa-f]{1,4}:){0,1}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){3}|(?:(?:[0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4})?::(?:[0-9A-Fa-f]{1,4}:){2}|(?:(?:[0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}:|(?:(?:[0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})?::)(?:[0-9A-Fa-f]{1,4}:[0-9A-Fa-f]{1,4}|(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?))|(?:(?:[0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})?::[0-9A-Fa-f]{1,4}|(?:(?:[0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4})?::)|[Vv][0-9A-Fa-f]+\\.[A-Za-z0-9\\-._~!$&\'()*+,;=:]+)\\]|(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)|(?:[A-Za-z0-9\\-._~!$&\'()*+,;=]|%[0-9A-Fa-f]{2})*)(?::[0-9]*)?(?:\\\/(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*|\\\/(?:(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})+(?:\\\/(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*)?|(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})+(?:\\\/(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@]|%[0-9A-Fa-f]{2})*)*|)(?:\\?(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@\\\/?]|%[0-9A-Fa-f]{2})*)?(?:\\#(?:[A-Za-z0-9\\-._~!$&\'()*+,;=:@\\\/?]|%[0-9A-Fa-f]{2})*)?$', '') const str = `http://-ru.stackoverflow.-com/`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; if ((m = regex.exec(str)) !== null) { // 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