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]
  • Character class intersection
    [\w&&[^\d]]
  • 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
Processing...

Test String

Code Generator

Generated Code

const regex = /^((?<![\d\-\*])((\*\/)?([0-5]?[0-9])((\,|\-|\/)([0-5]?[0-9]))*|\*)[^\S\r\n]+((\*\/)?((2[0-3]|1[0-9]|[0-9]|00))((\,|\-|\/)(2[0-3]|1[0-9]|[0-9]|00))*|\*)[^\S\r\n]+((\*\/)?([1-9]|[12][0-9]|3[01])((\,|\-|\/)([1-9]|[12][0-9]|3[01]))*|\*)[^\S\r\n]+((\*\/)?([1-9]|1[0-2])((\,|\-|\/)([1-9]|1[0-2]))*|\*|(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec))[^\S\r\n]+((\*\/)?[0-6]((\,|\-|\/)[0-6])*|\*|00|(sun|mon|tue|wed|thu|fri|sat)))$|^@(annually|yearly|monthly|weekly|daily|hourly|reboot)$/mg; // Alternative syntax using RegExp constructor // const regex = new RegExp('^((?<![\\d\\-\\*])((\\*\\\/)?([0-5]?[0-9])((\\,|\\-|\\\/)([0-5]?[0-9]))*|\\*)[^\\S\\r\\n]+((\\*\\\/)?((2[0-3]|1[0-9]|[0-9]|00))((\\,|\\-|\\\/)(2[0-3]|1[0-9]|[0-9]|00))*|\\*)[^\\S\\r\\n]+((\\*\\\/)?([1-9]|[12][0-9]|3[01])((\\,|\\-|\\\/)([1-9]|[12][0-9]|3[01]))*|\\*)[^\\S\\r\\n]+((\\*\\\/)?([1-9]|1[0-2])((\\,|\\-|\\\/)([1-9]|1[0-2]))*|\\*|(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec))[^\\S\\r\\n]+((\\*\\\/)?[0-6]((\\,|\\-|\\\/)[0-6])*|\\*|00|(sun|mon|tue|wed|thu|fri|sat)))$|^@(annually|yearly|monthly|weekly|daily|hourly|reboot)$', 'mg') const str = `#should pass: 5 4 * * sun * * * * * 0 22 * * 1-5 1 1 1 1 1 23 0-20/2 * * * * * * * * 0 0,12 1 */2 * 0 4 8-14 * * 0 0 1,15 * 3 @weekly 5 0 * 8 * 23 0-20/2 * * * 0 4 8-14 * * 0 0 1,15 * 3 @hourly 0 0,12 1 */2 * * * * feb * * 0-23/2 * * * * 0,2,4,6,8,10,12,14,16,18,20,22 * * * 50 0 * * * 45 00 * * 1-5 0,30 * * * * 0 0 * * * 00 00 * * * 0,30 * * * * 0 0,12 * * * 5 0 * * * 05 0 * * * 15 14 1 * * 0 22 * * 1-5 23 0-23/2 * * * * * * * 0-5 * * * 12-12 * * * * * 0-6 * * 30-31 * * 1-59 * * * * 00 00-00 * * * * * 30,31 * * 0 22 * * 1-5 23 0-20/2 * * * 23 10-20/10 * * * * * * * * * * * * * #should not pass: 23 55-20/10 * * * 1-60 * * * 1 3 * * * 50 * * * 20 50 1 * * 12-14 * 1 * * * 30 * * * * 0-8 5 * * * 8 * * * * 5,8 * * 30-34 * * 0 * * 0 1-4 0 0 0 12 * *-* * * * * * * *-1 * * *1 * 1 * * 1* * 1 * *`; // 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