RegExp Object in JavaScript:

In JavaScript Regular Expression is an object that defines a sequence of characters. This RegExp is use to search for a pattern. For example, you search something in a website by putting text in textbox at this time you can use this search pattern. The RegExp may be a simple character or may be more complicated sequence of characters. You can use RegExp to perform all types of text search operations.


Below we are defining RegExp in two patterns

var pattern = new RegExp(pattern, attributes);


var pattern = /pattern/attributes;

In above syntax we define two parameters of RegExp

  • pattern : it is a string which specifies the regular expression
  • attributes: it is an optional string which contain any attributes like ‘g’ means ‘global’, ‘I’ means ‘case-sensitive’ and ‘m’ means ‘multiline matches’

In RegExp brackets means square brackets ([]) and they are use to find a range of characters. Below is a list of expressions which are written in brackets.

Expression Description
[…..] Any one character b/w brackets
[^….] Any one character not b/w brackets
[0-9] Matches any decimal digit from 0 to 9
[a-z] Matches any character in lowercase from a to z
[A-Z] Matches any character in uppercase from A to Z
[a-Z] Matches any character from lowercase a to uppercase Z

Quantifiers in RegExp:

Here is a list of Quantifiers which is use to connect the character in a simple way or in a complicated pattern.

Expression Description
p+ Matches string containing at least one p
p* Matches string containing zero or more p’s
p? Matches string containing one or more p’s
p{N} Matches string containing a sequence of N p’s
p{2,3} Matches string containing a sequence two or three p’s
p{2, } Matches string containing a sequence of at least two p’s
p$ Matches string end with p
^p Matches string start with p


Below is table which will clear your concepts about character matching

Expression Description
[^a-zA-Z] Matches string not containing any of the characters ranging from a through z and A through Z
p.p Matches any string containing p, followed by any character, in turn followed by another p.
<b>(.*)</b> Matches any string enclosed within <b> and </b> tag


Here is a list of Modifiers that makes your RegExp much easier.

Modifiers Description
i Matches case sensitivity
m Specifies that if the string has newline or carriage return characters, the ^ and $ operators will now match against a newline boundary, instead of a string boundary
g Perform global matchin

One response to “RegExp Object in JavaScript”

  1. Samantha says:

    I discovered your Importance of RegExp in JavaScript |

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