正则表达式-学习2 - 语法语法学习重点详解

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匹配任何字符，除了换行符（any character except newline）

\w，\d ，\s

字符，数字，空白（word, digit, whitespace）

\W,\D,\S

非字符，非数字，非空白（ not word, digit, whitespace）

[abc]

any of a, b, or c 【中间没有任何字符分隔】

[^abc]

not a,b or c （出了个a,b,c其余的）

[a-g]

character between a & g

\b

匹配单词(word)边界位置，如空格，标点符号或字符串的开始/结尾。这匹配一个位置，而不是一个字符。(Matches a word boundary position such as whitespace, punctuation, or the start/end of the string. This matches a position, not a character.)

\B

匹配不是单词边界的任意位置，这匹配的是一个位置，不是一个字符。

\w

匹配任何单词字符（字母数字和下划线）。只匹配low-ascii字符（没有重音或非罗马字符）。相当于[A-Za-z0-9_](Matches any word character (alphanumeric & underscore). Only matches low-ascii characters (no accented or non-roman characters). Equivalent to [A-Za-z0-9_])

\W

Matches any character that is not a word character (alphanumeric & underscore). Equivalent to [^A-Za-z0-9_]

\d

Matches any digit character (0-9). Equivalent to [0-9].

\D

Matches any character that is not a digit character (0-9). Equivalent to [^0-9].

\s

Matches any whitespace character (spaces, tabs, line breaks(换行符)).

\S

Matches any character that is not a whitespace character (spaces, tabs, line breaks).

character set(字符集)[aeiou]

Match any character in the set.

negated set(非字符集)[^aeiou]

Match any character that is not in the set.

range: [a-z]

Matches a character having a character code between the two specified characters inclusive.(在两个指定的字符之间匹配具有字符代码的字符)

begining : ^

Matches the beginning of the string, or the beginning of a line if the multiline flag (m) is enabled. This matches a position, not a character. e.g.: /^\w+/gm -- He is a boy.

end: $

Matches the end of the string, or the end of a line if the multiline flag (m) is enabled. This matches a position, not a character. e.g.:/\w+$/g -- I am a girl_

word boundary(边界)\b

Matches a word boundary position such as whitespace(空白), punctuation(标点符号), or the start/end of the string. This matches a position, not a character. e.g.：/m\b/gm -- me em ;/\bm/gm -- me em ;

not word boundary \B

Matches any position that is not a word boundary. This matches a position, not a character. e.g.:/\w\B/gm --I am a girl_ me em

octal escape:\251

Octal(八进制) escaped character in the form \000. Value must be less than 255 (\377).（八进制需要转义的字符是从\000到\377（十进制的255））e.g.: /\255/g -- RegExr is ©2017.（其中©是被匹配的）

Hexadecimal(16进制) escape：\xA9

Hexadecimal escaped character in the form \xFF. e.g.: /\xA9/g -- RegExr is ©2017.（其中©是被匹配的）

Unicode escape：\u00A9

Unicode escaped character in the form \uFFFF. e.g.: /\u00A9/g -- RegExr is ©2017.（其中©是被匹配的）

control character escape

Escaped control character in the form \cZ. This can range from \cA (NULL, char code 0) to \cZ (EM, char code 25). e.g.: \cI matches TAB (char code 9).

tab: \t

Matches a TAB character (char code 9).

line feed : \n

Matches a LINE FEED character (char code 10 - 换行键).

vertical tab: \v

Matches a VERTICAL TAB character (char code 11 - 垂直制表符).

form feed:\f

Matches a FORM FEED character (char code 12-换行键).

carriage return :\r

Matches a CARRIAGE RETURN character (char code 13 - 回车键).

null : \0

Matches a NULL character (char code 0 - 空字符).

点.: \.

Matches a "." character (char code 46).

斜杠 \ : \\

Matches a "" character (char code 92).

+ ： \+

Matches a "+" character (char code 43).

* : \*

Matches a "*" character (char code 42).

？：\?

Matches a "?" character (char code 63).

^: \^

Matches a "^" character (char code 94).

$: \$

Matches a "$" character (char code 36).

[: \[

Matches a "[" character (char code 91).

]: \]

Matches a "]" character (char code 93).

{:\{

Matches a "{" character (char code 123).

}: \}

Matches a "}" character (char code 125).

(: \(

Matches a "(" character (char code 40).

): \)

Matches a ")" character (char code 41).

: \|

Matches a "|" character (char code 124).

/: \/

Matches a "/" character (char code 47).

capturing group(捕获组): (ABC)

将多个标记组合在一起，并创建一个提取子字符串或使用反向引用的捕获组。(Groups multiple tokens together and creates a capture group for extracting a substring or using a backreference.) (备注1)

backreference(对捕获组的反向引用): \1,\3, \num

Matches the results of a previous capture group. For example \1 matches the results of the first capture group & \3 matches the third. 对前面捕获分组的引用。 e.g. ： var str = 'abccab abc aba cbc dbd;'结果：str.match(/(\w)b\1/g) -> (3) ["aba", "cbc", "dbd"](\num代表捕获到的第一个值)

non-capturing group:(?:ABC)

Groups multiple tokens together without creating a capture group. (没有搞明白)

以下是断言

--

positive lookahead: (?=ABC)

Matches a group after the main expression without including it in the result. 向指定xxx后边肯定会出现ABC，就用正先行断言，表达式：(?=ABC) e.g.: \d(?=px) -- 1pt 2px 3em 4px

nagative lookahead: (?!ABC)

Specifies a group that can not match after the main expression (if it matches, the result is discarded). 向指定xxx后边肯定不会出现ABC，就用正先行断言，表达式：(?!ABC) e.g.: \d(?=px) -- 1pt 2px 3em 4px

plus: +

Matches 1 or more of the preceding token.

star: *

Matches 0 or more of the preceding token.

quantifier: {1,3}

Matches the specified quantity of the previous token. {1,3} will match 1 to 3. {3} will match exactly 3. {3,} will match 3 or more.

optional: ?

Matches 0 or 1 of the preceding token(上述标记), effectively making it optional.(使其成为可选项) eg. : /colou?r/g -- color colour

lazy: ?

Makes the preceding(前) quantifier(量词) lazy, causing it to match as few characters as possible. By default, quantifiers are greedy(贪婪的), and will match as many characters as possible. eg. : b\w+? -- b be bee beer beers

alternation:|

Acts like a boolean OR. Matches the expression before or after the |.It can operate within a group, or on a whole expression. The patterns will be tested in order.（它可以在一个小组内或者是整个表达内内运行，模式将按顺序进行测试） eg. :b(a|e|i)d -- bad bud bod bed bid

match:$&

Inserts the matched text. eg. 题目：'意见-rightClick-modal'.replace(/([^-]*)-/,'===$&====') 结果："===意见-====rightClick-modal"

capture group: $1

Inserts the results of the specified capture group. For example, $3 would insert the third capture group. 详细解释在下：1.2 捕获组编号规则

before match: $`

Inserts the portion of the source string that precedes the match.(插入匹配之前的源字符串部分)

after match : $'

Inserts the portion of the source string that follows the match.

escaped: $

Inserts a dollar sign character ($). e.g.. > test = 'abcdefg'; > test.replace(/ab(\w+?)[\D\d]*e(\w+?).*/g, '$2$') < "f$"

ignore case : i

Makes the whole expression case-insensitive(不区分大小写). For example, /aBc/i would match AbC.

global search: g

Retain the index of the last match, allowing subsequent(后续的) searches to start from the end of the previous match.

multiline: m

When the multiline flag is enabled, beginning and end anchors (^ and $) will match the start and end of a line, instead of the start and end of the whole string.((^ and $) 将匹配行的开始和结束，而不是整个字符串的开始和结束)

Unicode：u

When the unicode flag is enabled, you can use extended(扩展) unicode escapes in the form \x{FFFFF}.It also makes other escapes stricter, causing unrecognized escapes (ex. \j) to throw an error.

sticky:y

It also makes other escapes stricter, causing unrecognized escapes (ex. \j) to throw an error.(该表达式只能匹配lastIndex的位置，如果设置则忽略全局（g）标志。 由于RegExr中的每个搜索都是离散的，因此此标志对显示的结果没有进一步的影响。)

0

(\d{4})-(\d{2}-(\d\d))

2008-12-31

1

(\d{4})

2008

2

(\d{2}-(\d\d))

12-31

3

(\d\d)

31

0

(\d{4})-(\d{2}-(\d\d))

2008-12-31

1

(\d{4})

2008

2

(\d{2}-(\d\d))

12-31

3

(\d\d)

31