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.
Metacharacter Examples
Pattern
Sample Matches
^abc
abc, abcdefg, abc123, ...
abc$
abc, endsinabc, 123abc, ...
a.c
abc, aac, acc, adc, aec, ...
bill|ted
ted, bill
ab{2}c
abbc
a[bB]c
abc, aBc
(abc){2}
abcabc
ab*c
ac, abc, abbc, abbbc, ...
ab+c
abc, abbc, abbbc, ...
ab?c
ac, abc
a\sc
a c
Character Escapes
Escaped Char
Description
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
Char Class
Description
.
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.