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

/
/

Test String

Code Generator

Language

Generated Code

const regex = /^.*access-list([^\s]*\s){1}(?<src_acl>[^\s]+)\s([^\s]*\s){2}(?<src_iface>[a-z]+)\/(?<src_ip>[0-9.]+)\((?<src_port>[0-9]+)\)\s->\s(?<dest_iface>[a-z]+)\/(?<dest_ip>[0-9.]+)\((?<dest_port>[0-9]+)/; // Alternative syntax using RegExp constructor // const regex = new RegExp('^.*access-list([^\\s]*\\s){1}(?<src_acl>[^\\s]+)\\s([^\\s]*\\s){2}(?<src_iface>[a-z]+)\\\/(?<src_ip>[0-9.]+)\\((?<src_port>[0-9]+)\\)\\s->\\s(?<dest_iface>[a-z]+)\\\/(?<dest_ip>[0-9.]+)\\((?<dest_port>[0-9]+)', '') const str = `Aug 28 16:02:42 dmzfw-cal.mgmt.biz.lodh.com Aug 28 2015 16:02:42: %ASA-4-106100: access-list acl_dmzout permitted tcp dmzout/192.168.200.20(46301) -> outside/74.120.148.12(80) hit-cnt 1 first hit [0x35de8ee6, 0x0] `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; if ((m = regex.exec(str)) !== null) { // 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