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

/
/
g

Test String

Code Generator

Language

Generated Code

const regex = /({})\1|[{](|\s*?[^\s{}]+?\s*?|\s*?\S+?\(.*?\)\s*?|\s*?['][^']+?[']\s*?|\s*?["][^"]+?["]\s*?|\s*?["][^"]+?["]\.\S+?\(.*?\)\s*?|\s*?['][^']+?[']\.\S+?\(.*?\)\s*?)(?:!(\S+?))?[}]/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('({})\\1|[{](|\\s*?[^\\s{}]+?\\s*?|\\s*?\\S+?\\(.*?\\)\\s*?|\\s*?[\'][^\']+?[\']\\s*?|\\s*?["][^"]+?["]\\s*?|\\s*?["][^"]+?["]\\.\\S+?\\(.*?\\)\\s*?|\\s*?[\'][^\']+?[\']\\.\\S+?\\(.*?\\)\\s*?)(?:!(\\S+?))?[}]', 'g') const str = `{k} must-match {} jhtgj {} must-match { } not-match '"{firstName} {lastName}" <{email}>' {0.concat("8a b c d e", 6)} must-match s df s sd{"one fielslkein 897sd'f8'97f 89s(*Y*&Sc {}d name".toFixed(7 , 8)} must-match s df s sd{'one fielslkein "897sd"f897f 89s(*Y*&Sc {}d name'.toFixed(7 , 8)} must-match sd{0.concat("8a b c d e", 6)} must-match ascdac{ "one fieldname" } must-match ascdac{ "onefi eldname".kk(kk, "dd") } must-match {onefieldname.toFixed(7 , 8)} must-match dfgsdg { "onefieldname".toFixed(7 , 8)} must-match {onefieldname: "toFixed(7 , 8)"} not-match {"onefieldname": "toFixed(7 , 8)"} not-match { "onefiel dname" : "toFixed(7 , 8)"} not-match { "onefiel dname": 8} not-match { "o dna" : {onefi eldname.l(7 , 8)} } not-match { "o dna" : {"onefi eldname".l(7 , 8)} } match-inner { "f dna" : {"onefi eldname".toFixed(7 , 8) }} match-inner { "f dna" : { "onefi eldname".toFixed(7 , 8) }} match-inner { "o dme" : {onefieldname.toFixed(7 , 8)} } match-inner { "on dname" : { onefieldname.toFixed(7 , 8)} } match-inner { {}: "{}" }`; // 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