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 = /[a-zA-Z0-9.!#$%&’*+\/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)+/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('[a-zA-Z0-9.!#$%&’*+\\\/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\\.[a-zA-Z0-9-]+)+', 'gm') const str = `Envelope-to: login@site.ru Delivery-date: Fri, 27 Mar 2026 09:08:10 +0300 Authentication-Results: dkim=pass, header.i=@1-ofd.ru Received: from relay25.1-ofd.ru ([89.248.204.6]) by ruvip55.hostiman.ru with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.97.1) (envelope-from <echeck@1-ofd.ru>) id 1w60MX-000000007vc-3Zsb for login@site.ru; Fri, 27 Mar 2026 09:08:10 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=1-ofd.ru; s=mail; t=1774591685; bh=0o5X4pC1tr0unQQRyYpBU6TNm61Nwax1i1/3IcnrEtg=; h=Date:from:reply-to:to:Subject; b=PTMljcDJ3gVE0T6rQGcPrjSD0J9wF8l3o5MrWat0Pnagep+qDq42X/ZWJLpjdwM12 0fCF9SocQ0kdQzOZ6TM4/ehnUdG3jYkWwvT9Bg7PAJJJBlrmoykfT2kSGGAcuSbJbP KvjCHGADs9Wi1jEN3DTiJvKfYs+AR/piI0bBlcXA= Date: Fri, 27 Mar 2026 09:08:04 +0300 (MSK) from: =?UTF-8?B?0KfQtdC6INC4INC/0L7QtNCw0YDQvtC6?=<echeck@1-ofd.ru> reply-to: echeck@1-ofd.ru to: login@site.ru `; // 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