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 = /^acl\s(?P<acl_name>[^.\s]+)\s+\w+\s(?P<dest_domain>[-a-zA-Z0-9@:%._\+~#=]{1,256})/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^acl\\s(?P<acl_name>[^.\\s]+)\\s+\\w+\\s(?P<dest_domain>[-a-zA-Z0-9@:%._\\+~#=]{1,256})', 'gm') const str = `# log_mime_hdrs on # Turn off caching cache deny all # Disable ICMP pinger pinger_enable off # Consult local hosts file # hosts_file /etc/hosts # Set squid pidfile location pid_filename /var/run/squid/squid.pid # Set squid access logging location and use more human-readable format access_log stdio:/var/log/squid/access_combined.log logformat=combined access_log daemon:/var/log/squid/access_default.log logformat=squid # Set cache logging location cache_log /var/log/squid/cache.log # Do not allow caching me F5 BIG-IQ # Mgmt Self-Outside acl \$masked_host\$ src 20.20.30.4/32 160.11.44.56/32 # F5 BIG-IQ acl \$masked_host\$ src 20.20.30.132/32 160.11.44.184/32 # F5 BIG-IQ # External F5 # Mgmt Self-Outside Floating-Outside Self-Inside Floating-Inside acl \$masked_host\$ src 160.11.42.8/32 192.160.223.74/32 160.11.42.142/32 # External F5 BIG-IP acl \$masked_host\$ src 160.11.43.8/32 192.160.224.74/32 160.11.43.142/32 # External F5 BIG-IP # External F5 # Mgmt Self-Outside Floating-Outside Self-Inside Floating-Inside acl \$masked_host\$ src 160.11.42.4/32 192.160.223.4/32 192.160.223.46/32 160.11.42.132/32 160.11.42.140/32 # External F5 BIG-IP acl \$masked_host\$ src 160.11.42.6/32 192.160.223.5/32 192.160.223.46/32 160.11.42.138/32 160.11.42.140/32 # External F5 BIG-IP acl \$masked_host\$ src 160.11.43.4/32 192.160.224.4/32 192.160.224.46/32 160.11.43.132/32 160.11.43.140/32 # External F5 BIG-IP acl \$masked_host\$ src 160.11.43.6/32 192.160.224.5/32 192.160.224.46/32 160.11.43.138/32 160.11.43.140/32 # External F5 BIG-IP acl github_domains dstdomain .github.com acl clamav_domains dstdomain .clamav.net acl mozilla_org_domains dstdomain .mozilla.org acl mozilla_net_domains dstdomain .mozilla.net acl mozilla_com_domains dstdomain .mozilla.com acl google_domains dstdomain .google.com acl google_apis_domains dstdomain .googleapis.com acl powershell_domains dstdomain .digicert.com`; // 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