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

Language

Generated Code

const regex = /^(http:\/\/|https:\/\/)?[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}(:80|:443)?$|^(http:\/\/|https:\/\/)?\[[0-9a-fA-F:]+\](:80|:443)?$|^(http:\/\/|https:\/\/)?[0-9a-fA-F:]+(:80|:443)?$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(http:\\\/\\\/|https:\\\/\\\/)?[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}(:80|:443)?$|^(http:\\\/\\\/|https:\\\/\\\/)?\\[[0-9a-fA-F:]+\\](:80|:443)?$|^(http:\\\/\\\/|https:\\\/\\\/)?[0-9a-fA-F:]+(:80|:443)?$', 'gm') const str = `http://example.com https://example.com http://example.com:80 https://example.com:80 http://example.com:443 https://example.com:443 example.com:80 example.com:443 http://10.255.255.1 https://10.255.255.1 http://10.255.255.1:80 https://10.255.255.1:80 http://10.255.255.1:443 https://10.255.255.1:443 10.255.255.1:80 10.255.255.1:443 http://8.8.8.8 https://8.8.8.8 http://8.8.8.8:80 https://8.8.8.8:80 http://8.8.8.8:443 https://8.8.8.8:443 8.8.8.8:80 8.8.8.8:443 8.8.8.8 http://[fd00::1] https://[fd00::1] http://[fd00::1]:80 https://[fd00::1]:80 http://[fd00::1]:443 https://[fd00::1]:443 [fd00::1]:80 [fd00::1]:443 fd00::1:80 fd00::1:443 [fd00::1] fd00::1 http://[2001:0db8:85a3:0000:0000:8a2e:0370:7334] https://[2001:0db8:85a3:0000:0000:8a2e:0370:7334] http://[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:80 https://[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:80 http://[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:443 https://[2001:0db8:85a3:0000:0000:8a2e:0370:7334]:443 2001:0db8:85a3:0000:0000:8a2e:0370:7334:443 http://[2001:db8::1] https://[2001:db8::1] http://[2001:db8::1]:443 https://[2001:db8::1]:443 http://[2001:db8::1]:80 https://[2001:db8::1]:80 [2001:db8::1]:80 [2001:db8::1]:443 2001:db8::1:443 [2001:db8::1] http://[::1] https://[::1] http://[::1]:80 https://[::1]:80 http://[::1]:443 https://[::1]:443 [::1]:80 [::1]:443 `; // 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