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"
"
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

const regex = new RegExp('[^\\:]+:([\\d\\s]+\\s\\s).*', 'gm') const str = `0000000: 01010000 01001011 00000011 00000100 00010100 00000011 PK.... 0000006: 00000000 00000000 00001000 00000000 01000000 10001101 ....@. 000000c: 00101001 01000110 10011111 00101100 00000001 11100100 )F.,.. 0000012: 01111100 00101011 00000000 00000000 10111110 11010111 |+.... 0000018: 00000010 00000000 00001101 00000000 00000000 00000000 ...... 000001e: 01110000 01100001 01101110 01100100 01100001 01011111 panda_ 0000024: 01100010 01101001 01101110 00101110 01110100 01111000 bin.tx 000002a: 01110100 10101100 10011010 01001001 10101110 10011011 t..I.. 0000030: 01010000 00010000 01000101 11100111 01011001 10000101 P.E.Y. `; const subst = `$1\n`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result);

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