W3Schools.com

JavaScript RegExp Object

RegExp, is short for regular expression.

Complete RegExp Object Reference

For a complete reference of all the properties and methods that can be used with the RegExp object, go to our complete RegExp object reference.

The reference contains a brief description and examples of use for each property and method!

What is RegExp?

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

When you search in a text, you can use a pattern to describe what you are searching for.

A simple pattern can be one single character.

A more complicated pattern can consist of more characters, and can be used for parsing, format checking, substitution and more.

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

Syntax

var patt=new RegExp(pattern,modifiers);

or more simply:

var patt=/pattern/modifiers;
  • pattern specifies the pattern of an expression
  • modifiers specify if a search should be global, case-sensitive, etc.

RegExp Modifiers

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

The i modifier is used to perform case-insensitive matching.

The g modifier is used to perform a global match (find all matches rather than stopping after the first match).

Example 1

Do a case-insensitive search for "w3schools" in a string:

var str="Visit W3Schools";
var patt1=/w3schools/i;

The marked text below shows where the expression gets a match:

Visit W3Schools

Try it yourself »

Example 2

Do a global search for "is":

var str="Is this all there is?";
var patt1=/is/g;

The marked text below shows where the expression gets a match:

Is this all there is?

Try it yourself »

Example 3

Do a global, case-insensitive search for "is":

var str="Is this all there is?";
var patt1=/is/gi;

The marked text below shows where the expression gets a match:

Is this all there is?

Try it yourself »

test()

The test() method searches a string for a specified value, and returns true or false, depending on the result.

The following example searches a string for the character "e":

Example

var patt1=new RegExp("e");
document.write(patt1.test("The best things in life are free"));

Since there is an "e" in the string, the output of the code above will be:

true

Try it yourself »

exec()

The exec() method searches a string for a specified value, and returns the text of the found value. If no match is found, it returns null.

The following example searches a string for the character "e":

Example 1

var patt1=new RegExp("e");
document.write(patt1.exec("The best things in life are free"));

Since there is an "e" in the string, the output of the code above will be:

e

Try it yourself »

W3Schools Certification

W3Schools' Online Certification

The perfect solution for professionals who need to balance work, family, and career building.

More than 10 000 certificates already issued!

Get Your Certificate »

The HTML Certificate documents your knowledge of HTML.

The CSS Certificate documents your knowledge of advanced CSS.

The JavaScript Certificate documents your knowledge of JavaScript and HTML DOM.

The jQuery Certificate documents your knowledge of jQuery.

The XML Certificate documents your knowledge of XML, XML DOM and XSLT.

The ASP Certificate documents your knowledge of ASP, SQL, and ADO.

The PHP Certificate documents your knowledge of PHP and SQL (MySQL).

WEB HOSTING
Best Web Hosting
PHP MySQL Hosting
Best Hosting Coupons
UK Reseller Hosting
Cloud Hosting
Top Web Hosting
$7.95/mo SEO Hosting
Premium Website Design
WEB BUILDING
Download XML Editor
FREE Website BUILDER
Free Website Templates Free CSS Templates
Make Your Own Website
W3SCHOOLS EXAMS
Get Certified in:
HTML, CSS, JavaScript, XML, PHP, and ASP
W3SCHOOLS BOOKS
New Books:
HTML, CSS
JavaScript, and Ajax
STATISTICS
Browser Statistics
Browser OS
Browser Display
SHARE THIS PAGE