---
title: "JavaScript RegExp Object"  
description: "In this article I am going to explain you about the RegExp Object it is a short form of Regular Expression."  
author: "Danish Khan"  
published: 2012-10-19  
updated: 2019-11-21  
canonical: https://www.mindstick.com/articles/1048/javascript-regexp-object  
category: "javascript"  
tags: ["javascript"]  
reading_time: 9 minutes  

---

# JavaScript RegExp Object

[Introduction](https://yourviews.mindstick.com/view/85450/mesopotamia-introduction-to-an-ancient-civilization):\

In this article I am going to explain you about the RegExp Object it is a short form of [Regular Expression](https://www.mindstick.com/forum/65/regular-expression). Which are very important because they provide us pattern-matching, search and replacing of text possible in [JavaScript](https://www.mindstick.com/articles/874/how-to-create-watermark-text-for-textbox-by-using-javascript)?

##### Syntax:

```
    var pat=new RegExp(pattern,attributes);
    or more simply like

    var pat=/pattern/modifiers;
```

In the above syntax pattern specifies the expression which we are going to search for

And the [attributes](https://www.mindstick.com/articles/13105/2-attributes-that-make-your-odoo-ecommerce-theme-productive-and-engaging) specify that if a search is going to be global or case-sensitive etc.

##### Brackets:

Brackets have a special meaning when used with Regular Expression they are used basically to specify range of [characters](https://answers.mindstick.com/qa/42112/who-is-the-originator-of-avengers-characters).

| ## Expression | ## Description |
| --- | --- |
| ## [. . .] | Find any character between the bracket. |
| ## [^. . .] | Find any character not between the bracket. |
| ## [0 - 9] | It matches any decimal digits from 0-9. |
| ## [a – z] | It matches any character from lowercase letter a to lowercase letter z. |
| ## [A – Z] | It matches any character from uppercase letter A to uppercase letter Z. |
| ## [a –Z] | It matches any character from lowercase letter a to uppercase letter Z. |
|  |  |

The above ranges shown are general we can create our own like [0-6] it will match any decimal between 0 and 6 likewise we can match any characters [a-d], matches all the characters between character a to z.

##### Metacharacters:

Metacharacters are simply alphabetical characters which have special meaning; they are proceeding with a backslash which give a special meaning to the combination.

| ## Expression | ## Description |
| --- | --- |
| **.** | It is used to find a single character except newline or line terminator. |
| ## \w | It is used to find word character (a-z,A-Z,0-9 and Underscore). |
| ## \W | It is used to find a non-word character. |
| ## \d | It is used to find a digit from 0-9. |
| ## \D | It is used to find all non-digit character. |
| ## \s | It is used to find white space character (space,tab,newline) |
| ## \S | It is used to find non-whitespace character. |
| ## \b | It is used to find a match at the beginning of a word. |
| ## \B | It is used to find a match not at the beginning or end of a word. |
| ## \0 | It is used to find a NULL character. |
| ## \n | It is used to find a newline character. |
| ## \r | It is used to find a tab character. |

##### Quantifiers:

The frequency of bracketed characters and single characters can be denoted by a [special character](https://www.mindstick.com/forum/119/special-character-remove-from-url-or-any-string), each of the special character have some specific meaning.

| ## Quantifiers | ## Description |
| --- | --- |
| ## p+ | It will match any string which contains minimum one **p** or more. |
| ## p* | It will match any string that contains zero or more occurrences of **p**. |
| ## p? | It will match any string that contains zero or one occurrences of **p**. |
| ## p{N} | It will match any string that contains a sequence of N **p’s**. |
| ## p{x,y} | It will match any string that contains the sequence of x to y **p’s**. |
| ## p{x} | It matches any string that contains a sequence of at least x **p’s**. |
| ## p$ | It matches any string with **p** at the end of it. |
| ## ^p | It matches any string which is started at p. |
|  |  |

##### Example showing the use of RegExp:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is a first example of RegEx";
            var pattern1 = /example/;
            document.write(str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### output

example

##### \
RegExp Methods:

| ## Method | ## Description |
| --- | --- |
| ## exec() | It is used to execute a search for a string parameter passed to it. If no match found [returns null](https://www.mindstick.com/forum/159370/sql-join-returns-null-records-when-there-is-no-data-in-the-database-in-sql-server-why). |
| ## Test() | It searches string for text that matches regExp. It returns [true or false](https://www.mindstick.com/forum/160329/how-can-you-convert-a-value-to-a-boolean-true-or-false-in-javascript). |
| ## toString() | It returns the string representation of a specified object. |
| ## toSource() | It returns the object literal of the specified object and we can use this to create a new object |

Example of test method in RegExp:

```
 
<html xmlns="http://www.w3.org/1999/xhtml"><head>    <title>Regexp Example in JavaScript</title>    <script type="text/javascript">        function regExpress() {            var pattern1 = new RegExp("example");            document.write(pattern1.test("This is a example of test method"));        }    </script></head><body onload="regExpress()"> </body></html>
```

Output: true\

Example of exec method in RegExp:

```
<html xmlns="http://www.w3.org/1999/xhtml"><head>    <title>Regexp Example in JavaScript</title>    <script type="text/javascript">        function regExpress() {            var pattern1 = new RegExp("example");            document.write(pattern1.exec("This is a example of test method"));        }    </script></head><body onload="regExpress()"></body></html>
```

Output:

Example

##### Perform case-insensitive matching:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is a first Example of RegEx";
            var pattern1 = /example/i;
            document.write(str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### Output:

Example

##### Display all matches with the characters specified in the brackets:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is a first Example of RegEx";
            var pattern1 = /[a-f]/ig;
            document.write(str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### Output:

JavaScript RegExp Object

Example showing the use of Metacharacters

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is a first example of RegEx";
            var pattern1 = /ex.mple/;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

Output:

JavaScript RegExp Object

##### Example to find a word in a given string:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is a first example of RegEx";
            var pattern1 = /\w/g;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
 
```

##### This example will search for the non-word character:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "ab *&^ cd @! ef";
            var pattern1 = /\W/g;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### Output:

JavaScript RegExp Object

##### This example is used to search for digits:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "ab123cd456ef";
            var pattern1 = /\d/g;
            document.write("Metachar example: " + str.match(pattern1));
        }   
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### Output:

JavaScript RegExp Object

##### This example is to find out the non-digit characters:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "ab453!*fg45)(";
            var pattern1 = /\D/g;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### Output:

JavaScript RegExp Object

##### This example is to find out the white-space character :

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is example to find whitespace character";
            var pattern1 = /\s/g;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html>
```

##### \
Output:

JavaScript RegExp Object

##### This example is about the use of b metachar to find a match at the beginning of a word:

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Regexp Example in JavaScript</title>
    <script type="text/javascript">
        function regExpress() {
            var str = "This is example to find whitespace character";
            var pattern1 = /\bex/g;
            document.write("Metachar example: " + str.match(pattern1));
        }
    </script>
</head>
<body onload="regExpress()">
</body>
</html> 
```

##### Conclusion:

In this article I gave introduction to RegExp and what are the various uses in JavaScript through various examples.

\

---

Original Source: https://www.mindstick.com/articles/1048/javascript-regexp-object

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