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

Generated Code

const regex = /air_temp": ([\d.]+)/; // Alternative syntax using RegExp constructor // const regex = new RegExp('air_temp": ([\\d.]+)', '') const str = ` { "observations": { "notice": [ { "copyright": "Copyright Commonwealth of Australia 2017, Bureau of Meteorology. For more information see: http://www.bom.gov.au/other/copyright.shtml http://www.bom.gov.au/other/disclaimer.shtml", "copyright_url": "http://www.bom.gov.au/other/copyright.shtml", "disclaimer_url": "http://www.bom.gov.au/other/disclaimer.shtml", "feedback_url": "http://www.bom.gov.au/other/feedback" } ], "header": [ { "refresh_message": "Issued at 12:11 pm EST Tuesday 11 July 2017", "ID": "IDN60901", "main_ID": "IDN60902", "name": "Canberra", "state_time_zone": "NSW", "time_zone": "EST", "product_name": "Capital City Observations", "state": "Aust Capital Territory" } ], "data": [ { "sort_order": 0, "wmo": 94926, "name": "Canberra", "history_product": "IDN60903", "local_date_time": "11/12:00pm", "local_date_time_full": "20170711120000", "aifstime_utc": "20170711020000", "lat": -35.3, "lon": 149.2, "apparent_t": 5.7, "cloud": "Mostly clear", "cloud_base_m": 1050, "cloud_oktas": 1, "cloud_type_id": 8, "cloud_type": "Cumulus", "delta_t": 3.6, "gust_kmh": 11, "gust_kt": 6, "air_temp": 9.0, "dewpt": 0.2, "press": 1032.7, "press_qnh": 1031.3, "press_msl": 1032.7, "press_tend": "-", "rain_trace": "0.0", "rel_hum": 54, "sea_state": "-", "swell_dir_worded": "-", "swell_height": null, "swell_period": null, "vis_km": "10", "weather": "-", "wind_dir": "WNW", "wind_spd_kmh": 7, "wind_spd_kt": 4 }, { "sort_order": 1, "wmo": 94926, "name": "Canberra", "history_product": "IDN60903", "local_date_time": "11/11:30am", "local_date_time_full": "20170711113000", "aifstime_utc": "20170711013000", "lat": -35.3, "lon": 149.2, "apparent_t": 4.6, "cloud": "Mostly clear", "cloud_base_m": 900, "cloud_oktas": 1, "cloud_type_id": 8, "cloud_type": "Cumulus", "delta_t": 2.9, "gust_kmh": 9, "gust_kt": 5, "air_temp": 7.3, "dewpt": 0.1, "press": 1033.1, "press_qnh": 1031.7, "press_msl": 1033.1, "press_tend": "-", "rain_trace": "0.0", "rel_hum": 60, "sea_state": "-", "swell_dir_worded": "-", "swell_height": null, "swell_period": null, "vis_km": "10", "weather": "-", "wind_dir": "NW", "wind_spd_kmh": 4, "wind_spd_kt": 2 } ] } }`; // 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