JS Regular expression (reprint)

In JavaScript, the RegExp object represents a regular expression used to match a string.

One or two methods of definition:

1. Direct Volume Method:

/pattern/attribute

2. Object method:

New RegExp (Pattern,attribute);

Parameter description:

Pattern is a string that specifies the pattern of a regular expression or other regular expression;

attribute is an optional string that is used for pattern matching ranges, including i,g,m three characters, representing case-sensitive matching, global matching, and multiline matching, respectively. (if pattern is a regular expression and not a string, you must delete the parameter)

i-->ignorecase;

g-->gloable;

m-->multiline;

Second, the regular expression syntax description:

The syntax of a regular expression is described in seven ways, such as modifiers, brackets, metacharacters, quantifiers, RegExp object Properties, RegExp object methods, and methods that support a regular expression string object:

1. Modifier:

Modifier	Describe
I	Perform a match that is not case sensitive
G	Perform a full match (find all occurrences, not end after the first match is found)
M	Perform multi-line matching

2. Square brackets:

An expression	Describe
[ABCD]	Finds any character within a given set
[^ABCD]	Find any character that is not in a given collection
[0-9]	Find any number from 0 to 9
[A-z]	Find any lowercase letters from a to Z
[A-z]	Find any uppercase letters from A to Z
[A-z]	Find any letters from uppercase A to lowercase Z
[Red|blue|green]	Find any of the specified options

3, meta-character

if not

metacharacters	description
.	find any character, not including line break and line Terminator
\w	Find word characters, word characters include a-Z, A-Z, 0-9, and underline
\w	find non-word characters
\d	Find numbers
\d	Find non-numeric characters
\s	to find white space characters, including spaces, tabs, carriage returns, line feeds, vertical line breaks, and page breaks
\s	find non-whitespace characters
\b	matches word boundaries
\b	matches a non-word boundary
+	find null characters
\ n	finds a newline character, returns the location where the newline character was found, and returns 1
\f	Find a page break
\ r	Find carriage return
\ t	find tabs
\v	Find vertical Tabs
\xxx	find characters with octal number xxx
\xdd	to find characters specified in hexadecimal DD
\uxxxx	to find Unicode characters in hexadecimal xxxx

4. quantifier

Quantifiers	Describe
n+	Match a string that contains at least one n
N	Match a string containing 0 or more n
N?	Match a string containing 0 or 1 n
N{X}	Matches a string containing a sequence of x n
N{x,y}	Matches a string containing a sequence of x or y n
N{x,}	Matches a string that contains at least x N of a sequence
n$	Matches any string ending with n
^n	Matches any string that begins with n
!=0	Matches any string immediately followed by the specified string n
?! N	Matches any string that is not immediately followed by the specified string n

5. RegExp Object Properties

Property	Describe
Gloable	RegExp whether the object has a G flag, Regexpobject.global, returns a Boolean type
IgnoreCase	Whether the RegExp object has an I flag, Regexpobject.global, returns a Boolean type
Multiline	RegExp whether the object has an M flag, Regexpobject.global, returns a Boolean type
LastIndex	An integer that represents the next location to start matching
Source	Regular expression original text, returning the text used for pattern matching

6. RegExp Object method

Method	Describe
Compile	Compiles the regular expression. Usage: regexpobject.compile (regexp,modifier) modifier Specifies the type of matching-->i,m,g
Exec	Retrieves the value specified in the string, returns the found value and determines its location, or returns null if not found
Test	Retrieves the value specified in the string, returning a Boolean type. Used to determine whether a string matches a pattern, regexpobject.test (string)

7. Methods of String objects that support regular expressions

Method	Describe
Search	Retrieves a value that matches a regular expression or a specified substring. Usage: Stringobject.search (regexp)
Match	Matches a specified value or a string that matches one or more regular expressions. Usage: Stringobject.match (searchvalue); Stringobject.match (RegExp)
Replace	Replace other characters with some characters or replace substrings that match a regular expression. Usage: stringobject.replace (regexp/substr,replacement), the former is a substring or a regular expression to be replaced, the latter is the replacement text
Split	Used to split a string into an array of strings. Usage: stringobject.split (separator,howmany). The former must be a string or regular expression, starting at the location specified by the parameter.

JS Regular expression (reprint)