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 = /{"pm10":\s+(\d+(\.\d+)?)[^}]*}]/; // Alternative syntax using RegExp constructor // const regex = new RegExp('{"pm10":\\s+(\\d+(\\.\\d+)?)[^}]*}]', '') const str = `[{"pm10": 10.1, "pm25": 4.7, "time": "15.11.2019 13:01:49"}, {"pm25": 4.5, "pm10": 11.2, "time": "15.11.2019 13:07:21"}, {"pm10": 10.1, "pm25": 4.5, "time": "15.11.2019 13:12:54"}, {"pm25": 4.3, "pm10": 8.7, "time": "15.11.2019 13:18:26"}, {"pm10": 12.3, "pm25": 5.0, "time": "15.11.2019 13:23:58"}, {"pm25": 4.8, "pm10": 9.9, "time": "15.11.2019 13:29:31"}, {"pm10": 9.7, "pm25": 4.4, "time": "15.11.2019 13:35:03"}, {"pm25": 4.5, "pm10": 9.8, "time": "15.11.2019 13:40:35"}, {"pm10": 9.1, "pm25": 5.0, "time": "15.11.2019 13:46:08"}, {"pm25": 4.7, "pm10": 10.8, "time": "15.11.2019 13:51:40"}, {"pm10": 9.6, "pm25": 4.5, "time": "15.11.2019 13:57:13"}, {"pm25": 4.8, "pm10": 10.2, "time": "15.11.2019 14:02:45"}, {"pm10": 12.0, "pm25": 5.0, "time": "15.11.2019 14:08:17"}, {"pm25": 5.0, "pm10": 11.0, "time": "15.11.2019 14:13:50"}, {"pm10": 11.9, "pm25": 4.6, "time": "15.11.2019 14:19:22"}, {"pm25": 5.3, "pm10": 11.1, "time": "15.11.2019 14:24:54"}, {"pm10": 12.5, "pm25": 4.8, "time": "15.11.2019 14:30:27"}, {"pm25": 5.7, "pm10": 12.9, "time": "15.11.2019 14:35:59"}, {"pm10": 10.7, "pm25": 5.1, "time": "15.11.2019 14:41:32"}, {"pm25": 5.4, "pm10": 13.8, "time": "15.11.2019 14:47:04"}, {"pm10": 12.6, "pm25": 5.7, "time": "15.11.2019 14:52:36"}, {"pm25": 6.2, "pm10": 14.2, "time": "15.11.2019 15:10:09"}, {"pm10": 13.7, "pm25": 6.0, "time": "15.11.2019 15:15:41"}, {"pm25": 7.0, "pm10": 15.6, "time": "15.11.2019 15:16:58"}, {"pm10": 15.2, "pm25": 7.2, "time": "15.11.2019 15:22:28"}, {"pm25": 7.0, "pm10": 15.8, "time": "15.11.2019 16:51:10"}, {"pm10": 14.2, "pm25": 6.7, "time": "15.11.2019 16:56:42"}, {"pm25": 7.7, "pm10": 17.2, "time": "15.11.2019 16:58:32"}, {"pm10": 16.2, "pm25": 6.6, "time": "15.11.2019 17:04:04"}, {"pm25": 7.3, "pm10": 16.4, "time": "15.11.2019 17:09:37"}, {"pm10": 15.6, "pm25": 6.9, "time": "15.11.2019 17:15:09"}, {"pm25": 6.6, "pm10": 14.7, "time": "15.11.2019 17:20:42"}, {"pm10": 14.9, "pm25": 6.5, "time": "15.11.2019 17:26:14"}, {"pm25": 6.8, "pm10": 14.8, "time": "15.11.2019 17:31:46"}, {"pm10": 13.7, "pm25": 6.4, "time": "15.11.2019 17:37:19"}, {"pm25": 7.1, "pm10": 16.0, "time": "15.11.2019 17:50:58"}, {"pm10": 15.0, "pm25": 6.8, "time": "15.11.2019 17:52:08"}, {"pm25": 7.2, "pm10": 16.0, "time": "15.11.2019 17:57:40"}, {"pm10": 15.7, "pm25": 7.1, "time": "15.11.2019 18:03:13"}, {"pm25": 6.9, "pm10": 14.9, "time": "15.11.2019 18:08:45"}, {"pm10": 18.6, "pm25": 7.4, "time": "15.11.2019 18:14:17"}, {"pm25": 8.0, "pm10": 18.6, "time": "15.11.2019 18:19:50"}, {"pm10": 19.3, "pm25": 7.9, "time": "15.11.2019 18:25:22"}, {"pm25": 8.2, "pm10": 19.8, "time": "15.11.2019 18:30:54"}, {"pm10": 17.5, "pm25": 8.0, "time": "15.11.2019 18:36:27"}, {"pm25": 7.6, "pm10": 16.4, "time": "15.11.2019 18:41:59"}, {"pm10": 16.7, "pm25": 7.9, "time": "15.11.2019 18:47:31"}, {"pm25": 7.4, "pm10": 16.8, "time": "15.11.2019 18:53:04"}, {"pm10": 17.6, "pm25": 7.4, "time": "15.11.2019 18:58:36"}, {"pm25": 7.2, "pm10": 20.3, "time": "15.11.2019 19:04:09"}, {"pm10": 17.3, "pm25": 7.3, "time": "15.11.2019 19:09:41"}, {"pm25": 8.5, "pm10": 18.3, "time": "15.11.2019 19:15:13"}, {"pm10": 20.2, "pm25": 8.8, "time": "15.11.2019 19:20:46"}, {"pm25": 9.0, "pm10": 21.4, "time": "15.11.2019 19:26:18"}, {"pm10": 20.7, "pm25": 9.3, "time": "15.11.2019 19:31:50"}, {"pm25": 8.5, "pm10": 17.0, "time": "15.11.2019 19:37:23"}, {"pm10": 18.1, "pm25": 8.2, "time": "15.11.2019 19:42:55"}, {"pm25": 7.9, "pm10": 17.9, "time": "15.11.2019 19:48:28"}, {"pm10": 16.4, "pm25": 7.7, "time": "15.11.2019 19:54:00"}, {"pm25": 8.0, "pm10": 16.6, "time": "15.11.2019 19:59:32"}, {"pm10": 15.7, "pm25": 7.9, "time": "15.11.2019 20:05:05"}, {"pm25": 7.0, "pm10": 15.0, "time": "15.11.2019 20:10:37"}, {"pm10": 14.6, "pm25": 6.7, "time": "15.11.2019 20:16:09"}, {"pm25": 7.1, "pm10": 12.7, "time": "15.11.2019 20:21:42"}, {"pm10": 16.6, "pm25": 7.3, "time": "15.11.2019 20:27:14"}, {"pm25": 6.4, "pm10": 14.0, "time": "15.11.2019 20:32:47"}, {"pm10": 15.2, "pm25": 6.7, "time": "15.11.2019 20:38:19"}, {"pm25": 6.8, "pm10": 12.8, "time": "15.11.2019 20:43:51"}, {"pm10": 12.7, "pm25": 6.6, "time": "15.11.2019 20:49:24"}, {"pm25": 6.9, "pm10": 12.2, "time": "15.11.2019 20:54:56"}, {"pm10": 11.2, "pm25": 6.4, "time": "15.11.2019 21:00:28"}, {"pm25": 5.6, "pm10": 11.5, "time": "15.11.2019 21:06:01"}, {"pm10": 11.2, "pm25": 5.6, "time": "15.11.2019 21:11:33"}, {"pm25": 2.4, "pm10": 5.2, "time": "16.11.2019 08:50:54"}, {"pm10": 5.2, "pm25": 2.3, "time": "16.11.2019 08:56:27"}, {"pm25": 2.7, "pm10": 8.2, "time": "16.11.2019 09:01:59"}, {"pm10": 4.7, "pm25": 2.1, "time": "16.11.2019 09:07:32"}, {"pm25": 2.0, "pm10": 5.1, "time": "16.11.2019 09:13:04"}, {"pm10": 4.6, "pm25": 2.1, "time": "16.11.2019 09:18:36"}, {"pm25": 5.0, "pm10": 11.7, "time": "16.11.2019 13:16:41"}, {"pm10": 10.1, "pm25": 4.6, "time": "16.11.2019 13:22:11"}, {"pm25": 7.3, "pm10": 17.2, "time": "16.11.2019 15:36:53"}, {"pm10": 13.6, "pm25": 6.2, "time": "16.11.2019 15:42:25"}, {"pm25": 7.7, "pm10": 15.4, "time": "16.11.2019 17:02:49"}, {"pm10": 14.5, "pm25": 7.1, "time": "16.11.2019 17:08:22"}, {"pm25": 8.5, "pm10": 15.7, "time": "16.11.2019 17:38:24"}, {"pm10": 15.2, "pm25": 7.8, "time": "16.11.2019 17:43:57"}, {"pm25": 8.2, "pm10": 19.6, "time": "16.11.2019 17:49:29"}, {"pm10": 16.5, "pm25": 7.7, "time": "16.11.2019 17:55:01"}, {"pm25": 8.1, "pm10": 13.4, "time": "16.11.2019 20:46:43"}, {"pm10": 14.4, "pm25": 8.4, "time": "16.11.2019 20:52:15"}, {"pm25": 7.2, "pm10": 14.3, "time": "16.11.2019 20:57:48"}, {"pm10": 12.7, "pm25": 7.4, "time": "16.11.2019 21:03:20"}, {"pm25": 7.0, "pm10": 11.1, "time": "16.11.2019 21:08:52"}, {"pm10": 11.4, "pm25": 6.4, "time": "16.11.2019 21:14:25"}, {"pm25": 6.1, "pm10": 9.2, "time": "16.11.2019 21:38:13"}, {"pm10": 10.7, "pm25": 6.0, "time": "16.11.2019 21:43:45"}, {"pm25": 6.4, "pm10": 10.0, "time": "16.11.2019 21:49:18"}, {"pm10": 9.7, "pm25": 6.1, "time": "16.11.2019 21:54:50"}, {"pm25": 5.9, "pm10": 8.2, "time": "16.11.2019 22:00:22"}, {"pm10": 9.5, "pm25": 6.3, "time": "16.11.2019 22:05:55"}]`; // 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