This page provides an overall cheat sheet of all the capabilities of
RegExp
syntax by aggregating the content of the articles in the
RegExp
guide. If you need more information on a specific topic, please follow the link on the corresponding heading to access the full article or head to
the guide
.
| Characters | 含义 |
|---|---|
.
|
Has one of the following meanings:
注意，
ES2018 added the
|
\d
|
Matches any digit (Arabic numeral). Equivalent to
[0-9]
。例如，
/\d/
or
/[0-9]/
matches "2" in "B2 is the suite number".
|
\D
|
Matches any character that is not a digit (Arabic numeral). Equivalent to
[^0-9]
。例如，
/\D/
or
/[^0-9]/
matches "B" in "B2 is the suite number".
|
\w
|
Matches any alphanumeric character from the basic Latin alphabet, including the underscore. Equivalent to
[A-Za-z0-9_]
。例如，
/\w/
matches "a" in "apple", "5" in "$5.28", and "3" in "3D".
|
\W
|
Matches any character that is not a word character from the basic Latin alphabet. Equivalent to
[^A-Za-z0-9_]
。例如，
/\W/
or
/[^A-Za-z0-9_]/
matches "%" in "50%".
|
\s
|
Matches a single white space character, including space, tab, form feed, line feed, and other Unicode spaces. Equivalent to
[ \f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]
。例如，
/\s\w*/
matches " bar" in "foo bar".
|
\S
|
Matches a single character other than white space. Equivalent to
[^ \f\n\r\t\v\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]
。例如，
/\S\w*/
matches "foo" in "foo bar".
|
\t
|
Matches a horizontal tab. |
\r
|
Matches a carriage return. |
\n
|
Matches a linefeed. |
\v
|
Matches a vertical tab. |
\f
|
Matches a form-feed. |
[\b]
|
Matches a backspace. If you're looking for the word-boundary character (
\b
), see
Boundaries
.
|
\0
|
Matches a NUL character. Do not follow this with another digit. |
\c
X
|
Matches a control character using
caret notation
, where "X" is a letter from A–Z (corresponding to codepoints
U+0001
–
U+001F
). For example,
/\cM/
matches "\r" in "\r\n".
|
\x
hh
|
Matches the character with the code
hh
(two hexadecimal digits).
|
\u
hhhh
|
Matches a UTF-16 code-unit with the value
hhhh
(four hexadecimal digits).
|
\u
{hhhh}
or
\u{hhhhh}
|
(Only when the
u
flag is set.) Matches the character with the Unicode value
U+
hhhh
or
U+
hhhhh
(hexadecimal digits).
|
\
|
Indicates that the following character should be treated specially, or "escaped". It behaves one of two ways.
Note that some characters like
To match this character literally, escape it with itself. In other words to search for
|
| Characters | 含义 |
|---|---|
^
|
Matches the beginning of input. If the multiline flag is set to true, also matches immediately after a line break character. For example,
/^A/
does not match the "A" in "an A", but does match the first "A" in "An A".
This character has a different meaning when it appears at the start of a group . |
$
|
Matches the end of input. If the multiline flag is set to true, also matches immediately before a line break character. For example,
/t$/
does not match the "t" in "eater", but does match it in "eat".
|
\b
|
Matches a word boundary. This is the position where a word character is not followed or preceded by another word-character, such as between a letter and a space. Note that a matched word boundary is not included in the match. In other words, the length of a matched word boundary is zero. 范例：
To match a backspace character (
|
\B
|
Matches a non-word boundary. This is a position where the previous and next character are of the same type: Either both must be words, or both must be non-words, for example between two letters or between two spaces. The beginning and end of a string are considered non-words. Same as the matched word boundary, the matched non-word boundary is also not included in the match. For example,
/\Bon/
matches "on" in "at noon", and
/ye\B/
matches "ye" in "possibly yesterday".
|
注意
: The
?
character may also be used as a quantifier.
| Characters | 含义 |
|---|---|
x(?=y)
|
Lookahead assertion:
Matches "x" only if "x" is followed by "y". For example, /
Jack(?=Sprat)/
matches "Jack" only if it is followed by "Sprat".
/Jack(?=Sprat|Frost)/
matches "Jack" only if it is followed by "Sprat" or "Frost". However, neither "Sprat" nor "Frost" is part of the match results.
|
x(?!y)
|
Negative lookahead assertion:
Matches "x" only if "x"
is not followed by
"y"
.
例如，
/\d+(?!\.)/
matches a number only if it is not followed by a decimal point.
/\d+(?!\.)/.exec('3.141')
matches "141" but not "3".
|
(?<=y)x
|
Lookbehind assertion:
Matches "x" only if "x" is preceded by "y". For example,
/(?<=Jack)Sprat/
matches "Sprat" only if it is preceded by "Jack".
/(?<=Jack|Tom)Sprat/
matches "Sprat" only if it is preceded by "Jack" or "Tom". However, neither "Jack" nor "Tom" is part of the match results.
|
(?<!y)x
|
Negative lookbehind assertion:
Matches "x" only if "x" is not preceded by "y". For example,
/(?<!-)\d+/
matches a number only if it is not preceded by a minus sign.
/(?<!-)\d+/.exec('3')
matches "3".
/(?<!-)\d+/.exec('-3')
match is not found because the number is preceded by the minus sign.
|
| Characters | 含义 |
|---|---|
x
|
y
|
Matches either "x" or "y". For example,
/green|red/
matches "green" in "green apple" and "red" in "red apple".
|
[xyz]
|
A character set. Matches any one of the enclosed characters. You can specify a range of characters by using a hyphen, but if the hyphen appears as the first or last character enclosed in the square brackets it is taken as a literal hyphen to be included in the character set as a normal character. It is also possible to include a character class in a character set.
例如，
例如，
例如，
|
[^xyz]
|
A negated or complemented character set. That is, it matches anything that is not enclosed in the brackets. You can specify a range of characters by using a hyphen, but if the hyphen appears as the first or last character enclosed in the square brackets it is taken as a literal hyphen to be included in the character set as a normal character. For example,
[^abc]
如同
[^a-c]
. They initially match "o" in "bacon" and "h" in "chop".
The ^ character may also indicate the beginning of input . |
(
x
)
|
Capturing group:
Matches
x
and remembers the match. For example,
/(foo)/
matches and remembers "foo" in "foo bar".
A regular expression may have multiple capturing groups. In results, matches to capturing groups typically in an array whose members are in the same order as the left parentheses in the capturing group. This is usually just the order of the capturing groups themselves. This becomes important when capturing groups are nested. Matches are accessed using the index of the the result's elements (
Capturing groups have a performance penalty. If you don't need the matched substring to be recalled, prefer non-capturing parentheses (see below).
|
\
n
|
Where "n" is a positive integer. A back reference to the last substring matching the n parenthetical in the regular expression (counting left parentheses). For example,
/apple(,)\sorange\1/
matches "apple, orange," in "apple, orange, cherry, peach".
|
| \k<Name> |
A back reference to the last substring matching the
N
amed capture group
specified by
<Name>
.
例如，
|
(?<Name>x)
|
Named capturing group:
Matches "x" and stores it on the groups property of the returned matches under the name specified by
<Name>
. The angle brackets (
<
and
>
) are required for group name.
For example, to extract the United States area code from a phone number, we could use
|
(?:
x
)
|
Non-capturing group:
Matches "x" but does not remember the match. The matched substring cannot be recalled from the resulting array's elements (
[1], ..., [n]
) or from the predefined
RegExp
object's properties (
$1, ..., $9
).
|
注意： In the following, item refers not only to singular characters, but also includes character classes , Unicode 特性转义 , groups and ranges .
| Characters | 含义 |
|---|---|
x
*
|
Matches the preceding item "x" 0 or more times. For example,
/bo*/
matches "boooo" in "A ghost booooed" and "b" in "A bird warbled", but nothing in "A goat grunted".
|
x
+
|
Matches the preceding item "x" 1 or more times. Equivalent to
{1,}
。例如，
/a+/
matches the "a" in "candy" and all the "a"'s in "caaaaaaandy".
|
x
?
|
Matches the preceding item "x" 0 or 1 times. For example,
/e?le?/
matches the "el" in "angel" and the "le" in "angle."
If used immediately after any of the quantifiers
|
x
{
n
}
|
Where "n" is a positive integer, matches exactly "n" occurrences of the preceding item "x". For example,
/a{2}/
doesn't match the "a" in "candy", but it matches all of the "a"'s in "caandy", and the first two "a"'s in "caaandy".
|
x
{
n
,}
|
Where "n" is a positive integer, matches at least "n" occurrences of the preceding item "x". For example,
/a{2,}/
doesn't match the "a" in "candy", but matches all of the a's in "caandy" and in "caaaaaaandy".
|
x
{
n
,
m
}
|
Where "n" is 0 or a positive integer, "m" is a positive integer, and
m
>
n
, matches at least "n" and at most "m" occurrences of the preceding item "x". For example,
/a{1,3}/
matches nothing in "cndy", the "a" in "candy", the two "a"'s in "caandy", and the first three "a"'s in "caaaaaaandy". Notice that when matching "caaaaaaandy", the match is "aaa", even though the original string had more "a"s in it.
|
x
*?
x
+?
x
??
x
{n}?
x
{n,}?
x
{n,m}?
|
By default quantifiers like
*
and
+
are "greedy", meaning that they try to match as much of the string as possible. The
?
character after the quantifier makes the quantifier "non-greedy": meaning that it will stop as soon as it finds a match. For example, given a string like "some <foo> <bar> new </bar> </foo> thing":
|
// Non-binary values
\p{UnicodePropertyValue}
\p{UnicodePropertyName=UnicodePropertyValue}
// Binary and non-binary values
\p{UnicodeBinaryPropertyName}
// Negation: \P is negated \p
\P{UnicodePropertyValue}
\P{UnicodeBinaryPropertyName}
ASCII
,
Alpha
,
Math
,
Diacritic
,
Emoji
,
Hex_Digit
,
Math
,
White_space
, etc. See
Unicode Data PropList.txt
for more info.
gc
)
sc
)
scx
)
Decimal_Number
为
General_Category
property may be written
Nd
,
digit
，或
Decimal_Number
). For most values, the
UnicodePropertyName
part and equals sign may be omitted. If a
UnicodePropertyName
is specified, the value must correspond to the property type given.
注意： As there are many properties and values available, we will not describe them exhaustively here but rather provide various examples