字符类

字符类可以区分各种字符,例如区分字母和数字。

类型

Characters Meaning
.

有下列含义之一:

  • 匹配除行终止符之外的任何单个字符: \n, \r, \u2028 or \u2029. 例如, /.y/ 在“yes make my day”中匹配“my”和“ay”,而不是“yes”。
  • 在字符集内,点失去了它的特殊意义,并与文字点匹配。

需要注意的是,m multiline标志不会改变点的行为。因此,要跨多行匹配一个模式,可以使用字符集[^]—它将匹配任何字符,包括新行。

ES2018 添加了 s "dotAll" 标志,它允许点也匹配行终止符。

\d

匹配任何数字(阿拉伯数字)。 相当于 [0-9]. 例如, /\d/ 或 /[0-9]/ 匹配 “B2is the suite number”中的“2”。

\D

匹配任何非数字(阿拉伯数字)的字符。相当于[^0-9]. 例如, /\D/ or /[^0-9]/ 在 "B2 is the suite number" 中 匹配 "B".

\w

匹配基本拉丁字母中的任何字母数字字符,包括下划线。相当于 [A-Za-z0-9_]. 例如, /\w/ 在 "apple" 匹配 "a" , "5" in "$5.28", "3" in "3D" and "m" in "Émanuel".

\W

匹配任何不是来自基本拉丁字母的单词字符。相当于 [^A-Za-z0-9_]. 例如, /\W/ or /[^A-Za-z0-9_]/ 匹配 "%" 在 "50%" 以及 "É" 在 "Émanuel" 中.

\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]. For example, /\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]. For example, /\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.
\cX

Matches a control character using caret notation, where "X" is a letter from A–Z (corresponding to codepoints U+0001U+001F). For example, /\cM/ matches "\r" in "\r\n".

\xhh Matches the character with the code hh (two hexadecimal digits).
\uhhhh 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.

  • For characters that are usually treated literally, indicates that the next character is special and not to be interpreted literally. For example, /b/ matches the character "b". By placing a backslash in front of "b", that is by using /\b/, the character becomes special to mean match a word boundary.
  • For characters that are usually treated specially, indicates that the next character is not special and should be interpreted literally. For example, "*" is a special character that means 0 or more occurrences of the preceding character should be matched; for example, /a*/ means match 0 or more "a"s. To match * literally, precede it with a backslash; for example, /a\*/ matches "a*".

To match this character literally, escape it with itself. In other words to search for \ use /\\/.

Examples

Looking for a series of digits

var randomData = "015 354 8787 687351 3512 8735";
var regexpFourDigits = /\b\d{4}\b/g;
// \b indicates a boundary (i.e. do not start matching in the middle of a word)
// \d{4} indicates a digit, four times
// \b indicates another boundary (i.e. do not end matching in the middle of a word)


console.table(randomData.match(regexpFourDigits));
// ['8787', '3512', '8735']

Looking for a word (from the latin alphabet) starting with A

var aliceExcerpt = "I’m sure I’m not Ada,’ she said, ‘for her hair goes in such long ringlets, and mine doesn’t go in ringlets at all.";
var regexpWordStartingWithA = /\b[aA]\w+/g;
// \b indicates a boundary (i.e. do not start matching in the middle of a word)
// [aA] indicates the letter a or A
// \w+ indicates any character *from the latin alphabet*, multiple times

console.table(aliceExcerpt.match(regexpWordStartingWithA));
// ['Ada', 'and', 'at', 'all']

Looking for a word (from Unicode characters)

Instead of the Latin alphabet, we can use a range of Unicode characters to identify a word (thus being able to deal with text in other languages like Russian or Arabic). The "Basic Multilingual Plane" of Unicode contains most of the characters used around the world and we can use character classes and ranges to match words written with those characters.

var nonEnglishText = "Приключения Алисы в Стране чудес";
var regexpBMPWord = /([\u0000-\u0019\u0021-\uFFFF])+/gu;
// BMP goes through U+0000 to U+FFFF but space is U+0020

console.table(nonEnglishText.match(regexpBMPWord));
[ 'Приключения', 'Алисы', 'в', 'Стране', 'чудес' ]

Specifications

Specification
ECMAScript (ECMA-262)
RegExp: Character classes

Browser compatibility

For browser compatibility information, check out the main Regular Expressions compatibility table.

See also