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Other References

CSSStyleDeclaration JS Conversion

JavaScript. W3Schools in English. Lessons for beginners


JavaScript RegExp Reference

The RegExp Object

A regular expression is a pattern of characters.

The pattern is used for searching and replacing characters in strings.

The RegExp Object is a regular expression with added Properties and Methods.




let pattern = /w3schools/i;
Try it Yourself »

Example explained:

w3schoolsThe pattern to search for
/w3schools/A regular expression
/w3schools/iA case-insensitive regular expression

For a tutorial about Regular Expressions, read our JavaScript RegExp Tutorial.

Browser Support

/regexp/ is an ECMAScript1 (ES1) feature.

ES1 (JavaScript 1997) is fully supported in all browsers:

Chrome Edge Firefox Safari Opera IE
Yes Yes Yes Yes Yes Yes


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

Modifier Description
g Perform a global match (find all matches rather than stopping after the first match)
i Perform case-insensitive matching
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 character between the brackets (any digit)
[^0-9] Find any character NOT between the brackets (any non-digit)
(x|y) 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, beginning like this: \bHI, end like this: HI\b
\B Find a match, but not at the beginning/end of a word
\0 Find a NULL 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
\udddd Find the Unicode character specified by a hexadecimal number dddd


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 to 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

RegExp Object Properties

Property Description
constructor Returns the function that created the RegExp object's prototype
global Check whether the "g" modifier is set
ignoreCase Check whether the "i" modifier is set
lastIndex Specify the index at which to start the next match
multiline Check whether the "m" modifier is set
source Returns the text of the RegExp pattern

RegExp Object Methods

Method Description
compile() Deprecated in version 1.5. 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
toString() Returns the string value of the regular expression