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 = /(?<x_client_ip>.*?)\t-\t-\t.*?\t(?<http_status>.*?)\t(?<content_length>.*?)\t(?<referer>.*?)\t(?<user_agent>.*?)\t(?<method>.*?)\t(?<uri>.*?)\t(?<query_string>.*?)\t(?<protocol>.*?)\t(?<duration>.*?)\t-\t-\t-\t(?<id>.*)\t(?<client_ip>\d+\.\d+\.\d+\.\d+)\t/g; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?<x_client_ip>.*?)\\t-\\t-\\t.*?\\t(?<http_status>.*?)\\t(?<content_length>.*?)\\t(?<referer>.*?)\\t(?<user_agent>.*?)\\t(?<method>.*?)\\t(?<uri>.*?)\\t(?<query_string>.*?)\\t(?<protocol>.*?)\\t(?<duration>.*?)\\t-\\t-\\t-\\t(?<id>.*)\\t(?<client_ip>\\d+\\.\\d+\\.\\d+\\.\\d+)\\t', 'g') const str = `111.111.11.11 - - [17/Mar/2017:05:49:45 -0400] 302 231 "https://test.test.com/test/test/viewTest" "Mozilla/5.0 (Windows NT 10.0; WOW64) webWebKit/537.36 (KHTML, like Gecko) Web/56.0.2924.87 Safari/537.36" GET "/favicon.ico" "" HTTP/1.1 5236 - - - RES58cbb1390a02287220001fc146464dds 111.211.111.111 `; // 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