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

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /(\babstract\b)|(\bassert\b)|(\bboolean\b)|(\bbreak\b)|(\bbyte\b)|(\bcase\b)|(\bcatch\b)|(\bchar\b)|(\bclass\b)|(\bconst\b)|(\bcontinue\b)|(\bdefault\b)|(\bdouble\b)|(\bdo\b)|(\belse\b)|(\benum\b)|(\bextends\b)|(\bfalse\b)|(\bfinal\b)|(\bfinally\b)|(\bfloat\b)|(\bfor\b)|(\bgoto\b)|(\bif\b)|(\bimplements\b)|(\bimport\b)|(\binstanceof\b)|(\binterface\b)|(\bint\b)|(\blong\b)|(\bnative\b)|(\bnew\b)|(\bnull\b)|(\bpackage\b)|(\bprivate\b)|(\bprotected\b)|(\bpublic\b)|(\breturn\b)|(\bshort\b)|(\bstatic\b)|(\bstrictfp\b)|(\bsuper\b)|(\bswitch\b)|(\bsynchronized\b)|(\bthis\b)|(\bthrows\b)|(\bthrow\b)|(\btransient\b)|(\btrue\b)|(\btry\b)|(\bvoid\b)|(\bvolatile\b)|(\bwhile\b)/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(\\babstract\\b)|(\\bassert\\b)|(\\bboolean\\b)|(\\bbreak\\b)|(\\bbyte\\b)|(\\bcase\\b)|(\\bcatch\\b)|(\\bchar\\b)|(\\bclass\\b)|(\\bconst\\b)|(\\bcontinue\\b)|(\\bdefault\\b)|(\\bdouble\\b)|(\\bdo\\b)|(\\belse\\b)|(\\benum\\b)|(\\bextends\\b)|(\\bfalse\\b)|(\\bfinal\\b)|(\\bfinally\\b)|(\\bfloat\\b)|(\\bfor\\b)|(\\bgoto\\b)|(\\bif\\b)|(\\bimplements\\b)|(\\bimport\\b)|(\\binstanceof\\b)|(\\binterface\\b)|(\\bint\\b)|(\\blong\\b)|(\\bnative\\b)|(\\bnew\\b)|(\\bnull\\b)|(\\bpackage\\b)|(\\bprivate\\b)|(\\bprotected\\b)|(\\bpublic\\b)|(\\breturn\\b)|(\\bshort\\b)|(\\bstatic\\b)|(\\bstrictfp\\b)|(\\bsuper\\b)|(\\bswitch\\b)|(\\bsynchronized\\b)|(\\bthis\\b)|(\\bthrows\\b)|(\\bthrow\\b)|(\\btransient\\b)|(\\btrue\\b)|(\\btry\\b)|(\\bvoid\\b)|(\\bvolatile\\b)|(\\bwhile\\b)', 'gm') const str = `void main printf void/ public scanf super`; // 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