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

/
/
gm

Test String

Code Generator

Generated Code

const regex = /^(?<fulldomain>(?<protocol>[a-z]{2,6}):\/\/(?:((?<subdomain>[a-z0-9\-\.]*\.){0,99})(?<domain>[a-z\-0-9]{1,100})\.(?<extension>[a-z]{1,10})|(?<ipaddress>(?:25[0-5]|2[0-4]\d|[0-1]?\d{1,2})(?:\.(?:25[0-5]|2[0-4]\d|[0-1]?\d{1,2})){3})|(?<localhost>localhost))(?<port>\:[0-9]{1,6}){0,1})\/?(?<filepath>(?<path>[a-z0-9\-_%]{1,20}\/{1}){0,}(?<filename>[a-z0-9\-_]{1,20}\.[a-z0-9]{2,6}){0,1}){0,1}(?<route>(\/[a-z_0-9\-_]{1,20}){1,}){0,10}(?<query>\?[a-z0-9%\+_\-&=\.@\!,\:]{0,200}){0,1}$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?<fulldomain>(?<protocol>[a-z]{2,6}):\\\/\\\/(?:((?<subdomain>[a-z0-9\\-\\.]*\\.){0,99})(?<domain>[a-z\\-0-9]{1,100})\\.(?<extension>[a-z]{1,10})|(?<ipaddress>(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})(?:\\.(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})){3})|(?<localhost>localhost))(?<port>\\:[0-9]{1,6}){0,1})\\\/?(?<filepath>(?<path>[a-z0-9\\-_%]{1,20}\\\/{1}){0,}(?<filename>[a-z0-9\\-_]{1,20}\\.[a-z0-9]{2,6}){0,1}){0,1}(?<route>(\\\/[a-z_0-9\\-_]{1,20}){1,}){0,10}(?<query>\\?[a-z0-9%\\+_\\-&=\\.@\\!,\\:]{0,200}){0,1}$', 'gm') const str = `https://test.example.com:3000/path/to/page?q=1234&a=b&d=e https://lots.of.subs.test.example.com:3000/path/to/page?q=1234&a=b&d=e http://192.168.100.0:8080/path/to/page?q=123 http://localhost:3000/path/to/page?q=123 `; // 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