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 = /\[(?P<severity>\w+)\]\s*(?P<remote>[^\s:]+):(?P<port>\d+)\s*-\s*(?P<id>\d+)\s*"(?P<type>[\w]+)\s*(?P<class>\w+)\s*(?P<name>[^\s]+)\s*(?P<proto>\w+)\s*(?P<size>\d+)\s*(?P<do>\w+)\s*(?P<bufsize>\d+)"\s*(?P<rcode>\w+)\s*(?P<rflags>[^\s]+)\s+(?P<rsize>\d+)\s*(?P<duration>[^\s]+)/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('\\[(?P<severity>\\w+)\\]\\s*(?P<remote>[^\\s:]+):(?P<port>\\d+)\\s*-\\s*(?P<id>\\d+)\\s*"(?P<type>[\\w]+)\\s*(?P<class>\\w+)\\s*(?P<name>[^\\s]+)\\s*(?P<proto>\\w+)\\s*(?P<size>\\d+)\\s*(?P<do>\\w+)\\s*(?P<bufsize>\\d+)"\\s*(?P<rcode>\\w+)\\s*(?P<rflags>[^\\s]+)\\s+(?P<rsize>\\d+)\\s*(?P<duration>[^\\s]+)', 'gm') const str = `[INFO] 172.20.164.61:52054 - 29029 "AAAA IN private-link-api.coralogix.in. udp 47 false 512" NOERROR qr,aa,rd,ra 163 0.000061739s [INFO] 172.20.164.61:52054 - 15579 "A IN private-link-api.coralogix.in.ap-south-1.compute.internal. udp 75 false 512" NXDOMAIN qr,aa,rd,ra 190 0.000081757s [INFO] 172.20.164.61:52054 - 15579 "A IN private-link-api.coralogix.in.ap-south-1.compute.internal. udp 75 false 512" NXDOMAIN aa,rd,ra 190 0.000081757s [INFO] 172.20.160.191:44146 - 254 \\"A IN secretsmanager.ap-south-1.amazonaws.com. udp 57 false 512\\" NOERROR qr,aa,rd,ra 222 0.000054345s\\n","time":"2023-02-13T12:14:26.928909225Z`; // 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