About stdlib...
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
Return the index of the last element which equals a provided search element according to the SameValue Algorithm.
To use in Observable,
lastIndexOfSameValue = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-last-index-of-same-value@umd/browser.js' )To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var lastIndexOfSameValue = require( 'path/to/vendor/umd/array-base-last-index-of-same-value/index.js' )To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/array-base-last-index-of-same-value@umd/browser.js"></script>If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.lastIndexOfSameValue;
})();
</script>Returns the index of the last element which equals a provided search element according to the SameValue Algorithm.
var x = [ 1, 2, 3, 4, 5, 6 ];
var idx = lastIndexOfSameValue( x, 3, 5 );
// returns 2If the function is unable to find an element which equals a provided search element, the function returns -1.
var x = [ 1, 2, 3, 4, 5, 6 ];
var idx = lastIndexOfSameValue( x, 7, 5 );
// returns -1To begin searching from a specific index, provide a corresponding fromIndex argument.
var x = [ 1, 1, 2, 1, 2, 3, 3 ];
var idx = lastIndexOfSameValue( x, 2, 3 );
// returns 2If fromIndex is less than zero, the starting index is resolved relative to the last array element, with the last array element corresponding to fromIndex = -1.
var x = [ 1, 1, 2, 1, 2, 3, 3 ];
var idx = lastIndexOfSameValue( x, 2, -4 );
// returns 2- The function scans an input array from the starting index to the beginning of the array (i.e., backward).
- When searching for a search element, the function checks for equality using the SameValue Algorithm as specified in ECMAScript 5. As a consequence,
NaNvalues are considered equal, and-0and+0are considered distinct.
<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/array-base-last-index-of-same-value@umd/browser.js"></script>
<script type="text/javascript">
(function () {
var x = [ 'foo', 'bar', 'beep', 'boop', 'foo', 'bar' ];
var idx = lastIndexOfSameValue( x, 'beep', 5 );
// returns 2
idx = lastIndexOfSameValue( x, 'bop', 5 );
// returns -1
idx = lastIndexOfSameValue( x, 'foo', 5 );
// returns 4
idx = lastIndexOfSameValue( x, 'foo', -3 );
// returns 0
idx = lastIndexOfSameValue( x, 'foo', -50 );
// returns -1
})();
</script>
</body>
</html>This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
Copyright © 2016-2025. The Stdlib Authors.
