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

/
/
gi

Test String

Code Generator

Language

Generated Code

const regex = /r?call[\t ]+_(?!.*boot).*/gi; // Alternative syntax using RegExp constructor // const regex = new RegExp('r?call[\\t ]+_(?!.*boot).*', 'gi') const str = ` 88811 000294 00 A0 A9 bclr.b _RCONbits,#5 ;, 88813 000296 00 00 07 call _vBootInitSerialBuffer ; 88815 000298 F0 0E 20 mov #239,w0 ;, 88816 00029a 00 00 07 rcall _vBootInitSerial_C1 ; 88818 00029c F0 0E 20 mov #239,w0 ;, 88819 00029e 00 00 07 rcall _vBootInitSerial_C2 ; 88821 0002a0 00 40 EB clr.b w0 ; tmp38 88822 0002a2 00 E0 B7 mov.b WREG,_gbTurnOnLED ; gbTurnOnLED 89049 00032e E0 0F 50 sub w0,#0,[w15] ; tmp56, 89050 Call the routine 89051 000330 00 00 3A bra nz,.L50 ; 89053 000332 10 C0 B3 mov.b #1,w0 ;, 89054 000334 00 00 07 rcall _memcpy ; <HIT> 89055 000336 00 00 37 bra .L50 ; 89054 000334 00 00 07 rcall _BxootGGashLED ; <HIT> 89055 000336 00 00 37 bra .L50 ; 89054 000334 00 00 07 rcall _BootFlashLED ; 89054 000334 00 00 07 call _ln ; <HIT> 89055 000336 00 00 37 bra .L50 ; 89054 000334 00 00 07 call _vBoootFlashLED ; <HIT> 89055 000336 00 00 37 bra .L50 ; 89054 000334 00 00 07 rcall _u8BootGGashLED ; 89055 000336 00 00 37 bra .L50 ; 89054 000334 00 00 07 rcall _u16bootGGashLED ; 89055 000336 00 00 37 bra .L50 ; 89056 .L49: 89058 000338 00 00 80 mov _gu16_50HzTimerTick,w0 ;`; // 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