RegExp Object Overview

A regular expression is an object that describes a pattern of characters.

Regular expressions are used to perform pattern-matching and "search-and-replace" functions on text.

Creating a RegExp Object

To create a RegExp object, use the new keyword and assign the result to a variable.

The following example creates a RegExp named 'myRegExp':

var myRegExp = new RegExp(pattern, modifiers);

or

var myRegExp = /pattern/modifiers;

Modifiers are used to perform case-insensitive and global searches:

Modifier	Description
`i`	Perform case-insensitive matching
`g`	Perform a global match (find all matches rather than stopping after the first match)
`m`	Perform multiline matching

Brackets are used to find a range of characters:

Expression	Description
`[abc]`	Find any character between the brackets
`[^abc]`	Find any character not between the brackets
`[0-9]`	Find any digit from 0 to 9
`[A-Z]`	Find any character from uppercase A to uppercase Z
`[a-z]`	Find any character from lowercase a to lowercase z
`[A-z]`	Find any character from uppercase A to lowercase z
`[adgk]`	Find any character in the given set
`[^adgk]`	Find any character outside the given set
`(red\|blue\|green)`	Find any of the alternatives specified

Metacharacters are characters with a special meaning:

Metacharacter	Description
`.`	Find a single character, except newline or line terminator
`\w`	Find a word character
`\W`	Find a non-word character
`\d`	Find a digit
`\D`	Find a non-digit character
`\s`	Find a whitespace character
`\S`	Find a non-whitespace character
`\b`	Find a match at the beginning/end of a word
`\B`	Find a match not at the beginning/end of a word
`\0`	Find a NUL character
`\n`	Find a new line character
`\f`	Find a form feed character
`\r`	Find a carriage return character
`\t`	Find a tab character
`\v`	Find a vertical tab character
`\xxx`	Find the character specified by an octal number xxx
`\xdd`	Find the character specified by a hexadecimal number dd
`\uxxxx`	Find the Unicode character specified by a hexadecimal number xxxx

Quantifier	Description
`n+`	Matches any string that contains at least one n
`n*`	Matches any string that contains zero or more occurrences of n
`n?`	Matches any string that contains zero or one occurrences of n
`n{X}`	Matches any string that contains a sequence of X n's
`n{X,Y}`	Matches any string that contains a sequence of X or Y n's
`n{X,}`	Matches any string that contains a sequence of at least X n's
`n$`	Matches any string with n at the end of it
`^n`	Matches any string with n at the beginning of it
`?=n`	Matches any string that is followed by a specific string n
`?!n`	Matches any string that is not followed by a specific string n

Property	Description
`global`	Specifies if the "g" modifier is set
`ignoreCase`	Specifies if the "i" modifier is set
`lastIndex`	The index at which to start the next match
`multiline`	Specifies if the "m" modifier is set
`source`	The text of the RegExp pattern

Method	Description
`compile()`	Compiles a regular expression
`exec()`	Tests for a match in a string. Returns the first match
`test()`	Tests for a match in a string. Returns true or false