Metacharacters Defined

• ^ Start of a string.
• $ End of a string.
• . Any character (except \n newline)
• | Alternation.
• {...} Explicit quantifier notation.
• [...] Explicit set of characters to match.
• (...) Logical grouping of part of an expression.
• * 0 or more of previous expression.
• + 1 or more of previous expression.
• ? 0 or 1 of previous expression; also forces minimal matching when an expression might match several strings within a search string.
• ** Preceding one of the above, it makes it a literal instead of a special character. Preceding a special matching character, see below.

Character Escapes

ordinary characters Characters other than . $ ^ { [ ( | ) ] } * + ? \ match themselves.

• \a Matches a bell (alarm) \u0007.
• \b Matches a backspace \u0008 if in a []; otherwise matches a word boundary (between \w and \W characters).
• \t Matches a tab \u0009.
• \r Matches a carriage return \u000D.
• \v Matches a vertical tab \u000B.
• \f Matches a form feed \u000C.
• \n Matches a new line \u000A.
• \e Matches an escape \u001B.
• \040 Matches an ASCII character as octal (up to three digits); numbers with no leading zero are backreferences if they have only one digit or if they correspond to a capturing group number. (For more information, see Backreferences.) For example, the character \040 represents a space.
• \x20 Matches an ASCII character using hexadecimal representation (exactly two digits).
• \cC Matches an ASCII control character; for example \cC is control-C.
• \u0020 Matches a Unicode character using a hexadecimal representation (exactly four digits).
• * When followed by a character that is not recognized as an escaped character, matches that character. For example, * is the same - as \x2A.

Character Classes

• . Matches any character except \n. If modified by the Singleline option, a period character matches any character. For more information, see Regular Expression Options.
• [aeiou] Matches any single character included in the specified set of characters.
• [^aeiou] Matches any single character not in the specified set of characters.
• [0-9a-fA-F] Use of a hyphen (–) allows specification of contiguous character ranges.
• \p{name} Matches any character in the named character class specified by {name}. Supported names are Unicode groups and block ranges. For example, Ll, Nd, Z, IsGreek, IsBoxDrawing.
• \P{name} Matches text not included in groups and block ranges specified in {name}.
• \w Matches any word character. Equivalent to the Unicode character categories [\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \w is equivalent to [a-zA-Z_0-9].
• \W Matches any nonword character. Equivalent to the Unicode categories [^\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \W is equivalent to [^a-zA-Z_0-9].
• \s Matches any white-space character. Equivalent to the Unicode character categories [\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \s is equivalent to [ \f\n\r\t\v].
• \S Matches any non-white-space character. Equivalent to the Unicode character categories [^\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \S is equivalent to [^ \f\n\r\t\v].
• \d Matches any decimal digit. Equivalent to \p{Nd} for Unicode and [0-9] for non-Unicode, ECMAScript behavior.
• \D Matches any nondigit. Equivalent to \P{Nd} for Unicode and [^0-9] for non-Unicode, ECMAScript behavior.