Regular Expressions 101

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  • Unit Tests (18)

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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

/
/
gi

Test String

Code Generator

Language

Generated Code

const regex = /^(?=^[\w.@!#$%&'*+/=?^`{|}~-]{7,254}$)(?<username>(?=^[\w.!#$%&'*+/=?^`{|}~-]{1,64}@)[\w!#$%&'*+/=?^`{|}~-]+(?:\.[\w!#$%&'*+/=?^`{|}~-]+)*)@(?<domain>(?=\b[a-z\d.-]{5,252}$)(?:[a-z\d](?:[a-z\d-]{0,61}[a-z\d])\.)+(?:(?:[a-z](?:[a-z-]{0,61}[a-z]))|(?:(?=[a-z\d-]*?[a-z])(?=[a-z\d-]*?[\d])[a-z\d](?:[a-z\d-]{0,61}[a-z\d]))))$/gi; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(?=^[\\w.@!#$%&\'*+\/=?^`{|}~-]{7,254}$)(?<username>(?=^[\\w.!#$%&\'*+\/=?^`{|}~-]{1,64}@)[\\w!#$%&\'*+\/=?^`{|}~-]+(?:\\.[\\w!#$%&\'*+\/=?^`{|}~-]+)*)@(?<domain>(?=\\b[a-z\\d.-]{5,252}$)(?:[a-z\\d](?:[a-z\\d-]{0,61}[a-z\\d])\\.)+(?:(?:[a-z](?:[a-z-]{0,61}[a-z]))|(?:(?=[a-z\\d-]*?[a-z])(?=[a-z\\d-]*?[\\d])[a-z\\d](?:[a-z\\d-]{0,61}[a-z\\d]))))$', 'gi') const str = `Add the multiline (/m) Regex option for testing or go to te Unit Tests section... Valid addresses: test@email.com Test2@email.com another.test@email.com testwith+flag@email.com withanyofthese#!%\$'&+*-/=?^_.{|}~symbols@email.com upto64charactersusername56789c123456789d123456789e123456789f1234@email.com test@with.any.number.of.labels.separated.by.dots.email.com test@even.with.digits.1234567890.email.com test@and-hypens-email.com t@upto252charactersdomainname89c123456789d123456789e123456789f123.butonlyupto63charactersperlabel6789j123456789k123456789l1234567.9m123456789n123456789o123456789p123456789q123456789r123456789s1.3456789t123456789u123456789v123456789w123456789x12.email.com Invalid adresses: .usernamestartingwithdot@email.com usernameendingwithdot.@email.com havingtwo..consecutivedotsintheusername@email.com test@orinthedomainname..email.com test@having.all.numerical.top-level-domain.888 havinglessthan2characterperlabel@1.a.email.com (havingothersymbolsnotlisted)@email.com usingotherthanletters.digits.and-hyphens{anddots}inthedomainname@[123.45.67.89] `; // 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