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

r'
'
gm

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('^(?P<ip>\\d{1,3}.\\d{1,3}.\\d{1,3}.\\d{1,3}) - - \\[(?P<date>.*)\\] "(?P<request>.*?)" (?P<status>\\d*) (?P<size>\\d*) "(?P<referer>.*?)" "(?P<user_agent>.*?)".*$', 'gm') const str = `192.0.102.40 - - [09/Apr/2018:06:26:33 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:26:33 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 198.199.64.224 - - [09/Apr/2018:06:26:33 -0400] "POST /blog/wp-cron.php?doing_wp_cron=1523269593.5797910690307617187500 HTTP/1.1" 499 0 "-" "WordPress/4.9.5; https://ivoah.net/blog" 192.0.102.40 - - [09/Apr/2018:06:26:33 -0400] "HEAD /blog/ HTTP/1.1" 200 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:31:32 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:31:32 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 198.199.64.224 - - [09/Apr/2018:06:31:33 -0400] "POST /blog/wp-cron.php?doing_wp_cron=1523269893.1204290390014648437500 HTTP/1.1" 499 0 "-" "WordPress/4.9.5; https://ivoah.net/blog" 192.0.102.40 - - [09/Apr/2018:06:31:33 -0400] "HEAD /blog/ HTTP/1.1" 200 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:36:39 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:36:39 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 198.199.64.224 - - [09/Apr/2018:06:36:39 -0400] "POST /blog/wp-cron.php?doing_wp_cron=1523270199.4308791160583496093750 HTTP/1.1" 499 0 "-" "WordPress/4.9.5; https://ivoah.net/blog" 192.0.102.40 - - [09/Apr/2018:06:36:39 -0400] "HEAD /blog/ HTTP/1.1" 200 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 47.52.68.60 - - [09/Apr/2018:06:37:08 -0400] "POST /blog/2016/05/13/mate-on-raspberry-pi/?share=email&nb=1 HTTP/1.1" 302 5 "https://ivoah.net/blog/2016/05/13/mate-on-raspberry-pi/?share=email&nb=1" "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2)" 47.52.68.60 - - [09/Apr/2018:06:37:09 -0400] "GET /blog/2016/05/13/mate-on-raspberry-pi/?shared=email HTTP/1.1" 200 30602 "https://ivoah.net/blog/2016/05/13/mate-on-raspberry-pi/?share=email&nb=1" "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2)" 94.23.33.67 - - [09/Apr/2018:06:37:43 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 301 184 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 94.23.33.67 - - [09/Apr/2018:06:37:43 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 301 184 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 94.23.33.67 - - [09/Apr/2018:06:37:44 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 404 570 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 94.23.33.67 - - [09/Apr/2018:06:37:44 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 301 184 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 94.23.33.67 - - [09/Apr/2018:06:37:45 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 301 184 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 94.23.33.67 - - [09/Apr/2018:06:37:45 -0400] "GET //wp-content/plugins/cherry-plugin/admin/css/cherry-admin-plugin.css HTTP/1.0" 404 570 "-" "Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.94 Safari/537.36" 192.0.102.40 - - [09/Apr/2018:06:41:44 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 192.0.102.40 - - [09/Apr/2018:06:41:44 -0400] "HEAD /blog HTTP/1.1" 301 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 198.199.64.224 - - [09/Apr/2018:06:41:44 -0400] "POST /blog/wp-cron.php?doing_wp_cron=1523270504.8351509571075439453125 HTTP/1.1" 499 0 "-" "WordPress/4.9.5; https://ivoah.net/blog" 192.0.102.40 - - [09/Apr/2018:06:41:44 -0400] "HEAD /blog/ HTTP/1.1" 200 0 "-" "jetmon/1.0 (Jetpack Site Uptime Monitor by WordPress.com)" 207.244.149.74 - - [09/Apr/2018:06:45:38 -0400] "GET /wp-content/plugins/wp-formgenerator/assets/js/simpleslider.js HTTP/1.1" 404 341 "https://ivoah.net/wp-content/plugins/wp-formgenerator/assets/js/simpleslider.js" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/42.0.2311.152 Safari/537.36" 54.36.148.188 - - [09/Apr/2018:06:45:44 -0400] "GET /wp/audio/05042011.m4a HTTP/1.1" 301 184 "-" "Mozilla/5.0 (compatible; AhrefsBot/5.2; +http://ahrefs.com/robot/)" `; // 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