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

Generated Code

const regex = /^(?!-00:00)(?=^(?:Z|[\+\-](?:0[0-9]|1[012]):00|\+0[34569]:30|\+10:30|-03:30|-09:30|\+13:00|\+14:00|\+05:45|\+08:45|\+12:45))^((Z)|([\+\-])(\d\d):(\d\d))$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?!-00:00)(?=^(?:Z|[\\+\\-](?:0[0-9]|1[012]):00|\\+0[34569]:30|\\+10:30|-03:30|-09:30|\\+13:00|\\+14:00|\\+05:45|\\+08:45|\\+12:45))^((Z)|([\\+\\-])(\\d\\d):(\\d\\d))$', 'gm') const str = `// Time Zone UTC Offsets in actual use for ISO 8601 / RFC 3339 (Museum of Bad Data) // Accept: UTC indicator Z // Accept: Valid +xx:00 +00:00 +01:00 +02:00 +03:00 +04:00 +05:00 +06:00 +07:00 +08:00 +09:00 +10:00 +11:00 +12:00 +13:00 +14:00 // Accept: Valid -xx:00 -01:00 -02:00 -03:00 -04:00 -05:00 -06:00 -07:00 -08:00 -09:00 -10:00 -11:00 -12:00 // Accept: Valid +xx:30 +03:30 +04:30 +05:30 +06:30 +09:30 +10:30 // Accept: Valid +xx:45 +05:45 +08:45 +12:45 // Accept: Valid -xx:30 -03:30 -09:30 // Accept: Valid: 30 offsets +03:30 +04:30 +05:30 +06:30 +09:30 +10:30 -03:30 -09:30 // Accept: Valid :45 offsets +05:45 +08:45 +12:45 // Reject: valid RFC 3339, invalid ISO 8601 -00:00 // Reject: no such UTC offset in use -13:00 -14:00 +00:01 +00:03 +00:99 +20:00 +0:00 // Reject: no such UTC offset in use +01:30 +07:30 +08:30 +02:30 +11:30 +12:30 +13:30 +14:30 -01:30 -02:30 -04:30 -05:30 -06:30 -07:30 -08:30 -10:30 -11:30 -12:30 -13:30 -14:30 // Reject: Unused :45 offsets +01:45 +02:45 +03:45 +04:45 +06:45 +07:45 +09:45 +10:45 +11:45 +13:45 +14:45 -01:45 -02:45 -03:45 -04:45 -05:45 -06:45 -07:45 -08:45 -09:45 -10:45 -11:45 -12:45 -13:45 -14:45 +01:15 +02:15 +03:15 +04:15 +05:15 +06:15 +07:15 +08:15 +09:15 +10:15 +11:15 +12:15 +13:15 +14:15 -01:15 -02:15 -03:15 -04:15 -05:15 -06:15 -07:15 -08:15 -09:15 -10:15 -11:15 -12:15 -13:15 -14:15 // Reject: Z stands alone Z00:00 Z00 Z0 // Reject: hyphen required 0100 +0100 -0100 // Reject: colon required +0100 // Reject: No extra characters 2001-02-03T04:05:06.007+0800 +08:00 +08:00 \`\`\` ### Expanded Pattern: \`\`\` ^(?!-00:00)(?=^(?:Z|[\\+\\-](?:0[0-9]|1[012]):00|\\+0[34569]:30|\\+10:30|-03:30|-09:30|\\+13:00|\\+14:00|\\+05:45|\\+08:45|\\+12:45))^((Z)|([\\+\\-])(\\d\\d):(\\d\\d))\$ \`\`\` \`\`\` ^ # use zero-width assertions to capture all the special cases: (?!-00:00) # not -00:00 (?=^(?: Z # Z alone works, |[\\+\\-](?:0[0-9]|1[012]):00 # and all other +/- xx:00s, |\\+0[34569]:30|\\+10:30|-03:30|-09:30 # the +/- xx:30s. |\\+13:00|\\+14:00|\\+05:45|\\+08:45|\\+12:45 # and these special cases )) # Now that we've forced only positive matches, let's capture the pieces: ^( # G1: the whole offset (Z) | # G2: UTC indicator or nil ([\\+\\-]) # G3: +/- direction (\\d\\d) # G4: "hours" part of offset : (\\d\\d) # G5: "minutes" part of offset )\$ \`\`\` `; // 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