JavaScript lastIndex Property: RegExp Object


The lastIndex property is a read/write integer of RegExp object specifies the index at which to start the next match.


Implemented in JavaScript 1.2




The following web document demonstrates how the lastIndex property can be used.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<title>JavaScript Regexp lastIndex Property : Example-1</title>
<h1 style="color: red">JavaScript lastIndex constructor Property</h1>
<hr />
<script type="text/javascript">
//This is done to make the following JavaScript code compatible to XHTML. <![CDATA[
// Declare a regular expression for “The”
// Declare a string.
str1 = "The Quick Brown Fox Jumps Over The Lazy Dog";
// Executes search for pattern match with exec() and store result in an array array1
array1 = rexp.exec(str1);
document.write("The pattern '"+array1[0] + "' is matched Next match starts at index : " + rexp.lastIndex);

View the example in the browser

Supported Browser

Internet Explorer 7 Firefox 3.6 Google Chrome 7 Safari 5.0.1 Opera 10
Yes Yes Yes Yes Yes

See also:

JavaScript Core objects, methods, properties.

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JavaScript: Tips of the Day

Sort Number Arrays

JavaScript arrays come with a built-in sort method. This sort method converts the array elements into strings and performs a lexicographical sort on it by default. This can cause issues when sorting number arrays. Hence here is a simple solution to overcome this problem.

[0,10,4,9,123,54,1].sort((a,b) => a-b);
>>> [0, 1, 4, 9, 10, 54, 123]

You are providing a function to compare two elements in the number array to the sort method. This function helps us the receive the correct output.

Ref: https://bit.ly/3adlwNy