npm package: @stdlib/string-substring-before-last
Description: Return the part of a string before the last occurrence of a specified substring.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>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.</p>
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# substringBeforeLast

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Return the part of a string before the last occurrence of a specified substring.

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/string-substring-before-last
```

</section>

<section class="usage">

## Usage

```javascript
var substringBeforeLast = require( '@stdlib/string-substring-before-last' );
```

#### substringBeforeLast( str, search )

Returns the part of a string before the last occurrence of a specified substring.

```javascript
var str = 'Beep Boop Beep';
var out = substringBeforeLast( str, 'Beep' );
// returns 'Beep Boop '

out = substringBeforeLast( str, 'Boop' );
// returns 'Beep '
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   If a substring is not present in a provided string, the function returns the input string.
-   If provided an empty substring, the function returns the input string.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var substringBeforeLast = require( '@stdlib/string-substring-before-last' );

var str = 'beep boop';
var out = substringBeforeLast( str, ' ' );
// returns 'beep'

out = substringBeforeLast( str, 'e' );
// returns 'be'

out = substringBeforeLast( str, 'x' );
// returns 'beep boop'

out = substringBeforeLast( str, '' );
// returns 'beep boop'
```

</section>

<!-- /.examples -->

<!-- Section for describing a command-line interface. -->



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</section>

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<section class="related">

## See Also

-   <span class="package-name">[`@stdlib/string-substring-before-last-cli`][@stdlib/string-substring-before-last-cli]</span><span class="delimiter">: </span><span class="description">CLI package for use as a command-line utility.</span>
-   <span class="package-name">[`@stdlib/string-substring-before`][@stdlib/string/substring-before]</span><span class="delimiter">: </span><span class="description">return the part of a string before a specified substring.</span>
-   <span class="package-name">[`@stdlib/string-substring-after`][@stdlib/string/substring-after]</span><span class="delimiter">: </span><span class="description">return the part of a string after a specified substring.</span>
-   <span class="package-name">[`@stdlib/string-substring-after-last`][@stdlib/string/substring-after-last]</span><span class="delimiter">: </span><span class="description">return the part of a string after the last occurrence of a specified substring.</span>

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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<section class="links">

[@stdlib/string-substring-before-last-cli]: https://www.npmjs.com/package/@stdlib/string-substring-before-last-cli

[npm-image]: http://img.shields.io/npm/v/@stdlib/string-substring-before-last.svg
[npm-url]: https://npmjs.org/package/@stdlib/string-substring-before-last

[test-image]: https://github.com/stdlib-js/string-substring-before-last/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/string-substring-before-last/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/string-substring-before-last/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/string-substring-before-last?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[cli-section]: https://github.com/stdlib-js/string-substring-before-last#cli
[cli-url]: https://github.com/stdlib-js/string-substring-before-last/tree/cli
[@stdlib/string-substring-before-last]: https://github.com/stdlib-js/string-substring-before-last/tree/main

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/string-substring-before-last/tree/deno
[deno-readme]: https://github.com/stdlib-js/string-substring-before-last/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/string-substring-before-last/tree/umd
[umd-readme]: https://github.com/stdlib-js/string-substring-before-last/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/string-substring-before-last/tree/esm
[esm-readme]: https://github.com/stdlib-js/string-substring-before-last/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/string-substring-before-last/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/string-substring-before-last/main/LICENSE

[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams

[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

<!-- <related-links> -->

[@stdlib/string/substring-before]: https://www.npmjs.com/package/@stdlib/string-substring-before

[@stdlib/string/substring-after]: https://www.npmjs.com/package/@stdlib/string-substring-after

[@stdlib/string/substring-after-last]: https://www.npmjs.com/package/@stdlib/string-substring-after-last

<!-- </related-links> -->

</section>

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