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

@"
"
g

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('\\(\\?\\(DEFINE\\)(?<definition>(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\(\\?\\<(?<name>[\\w-[0-9]]\\w*?)\\>(?<content>(?#internals shallow)(?:(?:(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\[(?:(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])(?:\\\\\\[|\\\\\\])|[^\\[\\]])*(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\])|(?:(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\(\\?(?:\\!|\\=|\\:|\\<\\!|\\<\\=)(?#internals deep)(?:(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])(?:\\\\\\(|\\\\\\)|\\\\\\[|\\\\\\])|[^\\(\\)\\[\\]])+(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\))|(?:(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])(?:\\\\\\(|\\\\\\)|\\\\\\[|\\\\\\])|[^\\(\\)\\[\\]]))+)(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\))*(?<=(?:[^\\\\](?:\\\\\\\\)+)|[^\\\\])\\)', 'g') const str = `(?(DEFINE)(?<internal_name_char_s>[^\\x85\\n\\r\\v\\t\\\\\\/\\:\\*\\"\\?\\<\\>\\|])(?<external_filesc_name_char_s>[^\\x85\\n\\r\\v\\t\\\\\\/\\:\\*\\"\\?\\<\\>\\|\\s])(?<external_folderesc_name_char_s>[^\\x85\\n\\r\\v\\t\\\\\\/\\:\\*\\"\\?\\<\\>\\|\\s\\.])(?<folder_name_s>\\g'external_filesc_name_char_s'\\g'internal_name_char_s'{1,258}\\g'external_filesc_name_char_s'|\\g'external_folderesc_name_char_s'\\g'external_filesc_name_char_s'|\\g'external_filesc_name_char_s'\\g'external_folderesc_name_char_s'|\\g'external_folderesc_name_char_s')(?<extension_char_s>[a-z0-9])(?<extension_s>\\g'extension_char_s'{1,260})(?<file_name_s>(?:\\g'external_filesc_name_char_s'\\g'internal_name_char_s'{1,258}\\g'external_filesc_name_char_s'|\\g'external_filesc_name_char_s'{1,2})(?=\\.\\g'extension_s'\\Z))(?<ipv4_number_s>(?:[12]\\d\\d)|(?:\\d\\d)|(?:\\d))(?<ipv4_s>(?:\\g'ipv4_number_s'\\.){3}\\g'ipv4_number_s'(?:\\:\\d+)?)(?<named_drive_root_s>[a-z]\\:\\/)(?<file_protocol_root_s>file\\:\\/\\/\\/\\g'named_drive_root_s')(?<smb_root_s>\\/\\/)(?<hyper_text_root_s>https?\\:\\/\\/))(?#definition is complete)\\A(?!\\Z)(?<all_until_last_name>(?<root>(?<fixed_root>\\/|\\g'named_drive_root_s'|\\g'file_protocol_root_s'|(?<remote_root>\\g'smb_root_s'|\\g'hyper_text_root_s')(?:(?<ipv4>\\g'ipv4_s')(?:\\/(?!\\Z)|))?)|(?<relative_root>\\.{1,2}\\/(?:\\.\\.\\/)*))?(?<body>(?:\\g'folder_name_s'\\/)*?))(?<last_folder_or_file_name>(?<file_full_name>(?<file_short_name>\\g'file_name_s')\\.(?:(?<shortcut_extension>lnk)|(?<remote_extension>url)|(?<general_extension>\\g'extension_s'))(?!\\/))|(?:(?<folder_name>\\g'folder_name_s')\\/?))?\\Z`; // 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