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

/
/
gmi

Test String

Code Generator

Language

Generated Code

const regex = /^((^\+44)|^(4{2})|(^0{2}4{2})|(^0)|)([123789])\d{8,9}$/gmi; // Alternative syntax using RegExp constructor // const regex = new RegExp('^((^\\+44)|^(4{2})|(^0{2}4{2})|(^0)|)([123789])\\d{8,9}$', 'gmi') const str = `+44123456789 +441234567890 +44123456789 +441234567890 +447921040642 +441234567890 +44123456789 +44123456789 +441234567890 +44123456789 441234567890 44123456789 441234567890 447921040642 441234567890 44123456789 44123456789 441234567890 07921040642 0123456789 01234567890 0123456789 01234567890 01932867083 00441234567 0845121212 0044123456789 00441234567890 0123456789 01234567890 0123456789 01234567890 01932867083 00441234567 0044123456789 00441234567890 0044123456789 00441234567890 08006444454 4451925858 01420383091 112222222 111111111`; // 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