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"
"
g

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('\\b(?:[0-9]{1,3}\\.){3}[0-9]{1,3}\\b', 'g') const str = `Return-path: <Walk-in.Whirlpool.Tubs@familywhitetubin.date> Envelope-to: jblumberg@menshealthandwellness.org Delivery-date: Mon, 31 Aug 2015 15:38:19 -0400 Received: from [50.2.8.182] (port=34151 helo=familywhitetubin.date) by host.menshealthandwellness.org with esmtp (Exim 4.85) (envelope-from <Walk-in.Whirlpool.Tubs@familywhitetubin.date>) id 1ZWUuJ-0003hH-6L for jblumberg@menshealthandwellness.org; Mon, 31 Aug 2015 15:38:19 -0400 Date: Mon, 31 Aug 2015 12:47:39 -0700 Message-ID: <77f581ddf9662409a9e27aaac2f26d74.14325456.20579279@familywhitetubin.date> From: Walk-in.Whirlpool.Tubs <Walk-in.Whirlpool.Tubs@familywhitetubin.date> To: <jblumberg@menshealthandwellness.org> Dvhgo-Wu: 14325456i.20579279nr.o20579279 Content-Type: text/plain Mime-Version: 1.0 Subject: Enjoy Safe, Comfortable Bathing in your Jacuzzi Walk-In-Bath, Quote: 14325456 Mi-Tdx: 77f581ddf9662409a9e27aaac2f26d74t-20579279br.d14325456 `; // 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