JavaScript Object -- Regexp

Regexp object

The Regexp object represents a regular expression, which is a powerful tool for matching string execution modes.

Direct amount syntax

/Pattern/attributes

Syntax for creating a Regexp object:

New Regexp (Pattern,Attributes);

Parameters

ParametersPatternIs a string that specifies the regular expression mode or other regular expressions.

ParametersAttributesIt is an optional string that contains the "g", "I", and "M" attributes. It is used to specify global matching, case-sensitive matching, and multi-line matching, respectively. Before ecmascript standardization, the M attribute is not supported. IfPatternThis parameter must be omitted if it is a regular expression rather than a string.

Return Value

A new Regexp object with the specified pattern and flag. If the ParameterPatternIf it is a regular expression rather than a string, the Regexp () constructor creates a new Regexp object with the same pattern and flag as the specified Regexp.

If Regexp () is called as a function instead of the new operator, it performs the same behavior as when it is called using the new operator.PatternWhen it is a regular expression, it only returnsPatternInstead of creating a new Regexp object.

Throw

Syntaxerror-ifPatternIt is not a legal regular expression, orAttributesThis exception is thrown if it contains characters other than "g", "I", and "M.

Typeerror-ifPatternIt is a Regexp object, but it is not omittedAttributesParameter.

Modifier

Modifier	Description
I	Perform case-insensitive matching.
G	Perform global match (search for all matches instead of stopping the first match ).
M	Perform multi-row matching.

Square brackets

Square brackets are used to find characters in a certain range:

Expression	Description
[ABC]	Find any character between square brackets.
[^ ABC]	Search for any characters that are not in square brackets.
[0-9]	Search for any number ranging from 0 to 9.
[A-Z]	Search for any characters from lowercase to lowercase.
A-Z	Search for any characters from uppercase A to uppercase Z.
[A-Z]	Search for any characters from uppercase A to lowercase Z.
[Adgk]	Searches for any character in a given set.
[^ Adgk]	Searches for any characters outside the given set.
(Red | Blue | green)	Find any specified options.

Metacharacters

Metacharacter is a character with special meanings:

Metacharacters	Description
.	Searches for a single character, except for line breaks and line Terminators.
\ W	Search for word characters.
\ W	Searches for non-word characters.
\ D	Search for numbers.
\ D	Searches for non-numeric characters.
\ S	Search for blank characters.
\ S	Searches for non-blank characters.
\ B	Match the word boundary.
\ B	Match non-word boundary.
\ 0	Search for NUL characters.
\ N	Find a line break.
\ F	Find a break.
\ R	Find the carriage return.
\ T	Search for tabs.
\ V	Search for vertical tabs.
\ Xxx	Search for characters specified by octal XXX.
\ Xdd	Search for the characters specified by DD in hexadecimal notation.
\ Uxxxx	Find the Unicode characters specified by the hexadecimal number XXXX.

Quantifiers

Quantifiers	Description
N +	Match any string containing at least one N.
N *	Match any string containing zero or more N.
N?	Match any string containing zero or one N.
N {x}	Matches the string that contains x N sequences.
N {x, y}	Matches the string that contains X or Y n.
N {X ,}	Matches strings that contain at least x N sequences.
N $	Match any string ending with N.
^ N	Match any string starting with N.
? = N	Match any string followed by the specified string n.
?! N	Match any string that is not followed by the specified string n.

Regexp Object Attributes

FF: Firefox, ie: Internet Explorer

Attribute	Description	FF	IE
Global	Whether the Regexp object has a flag.	1	4
Ignorecase	Whether the Regexp object has a flag I.	1	4
Lastindex	An integer that indicates the position of the next matched character.	1	4
Multiline	Whether the Regexp object has a flag M.	1	4
Source	The Source Text of the regular expression.	1	4

Regexp object Method

FF: Firefox, ie: Internet Explorer

Method	Description	FF	IE
Compile	Compile a regular expression.	1	4
Exec	Returns the value specified in the string. Return the value found and locate it.	1	4
Test	Returns the value specified in the string. Returns true or false.	1	4

Methods for string objects that support regular expressions

FF: Firefox, ie: Internet Explorer

Method	Description	FF	IE
Search	Returns the value that matches the regular expression.	1	4
Match	Find the matching of one or more regular expressions.	1	4
Replace	Replace the substring that matches the regular expression.	1	4
Split	Splits a string into a string array.	1	4