npm package: @stdlib/string-prev-grapheme-cluster-break
Description: Return the previous extended grapheme cluster break in a string before a specified position.
Author: The Stdlib Authors
Latest version: 0.2.3

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# prevGraphemeClusterBreak

[![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 previous extended grapheme cluster break in a string before a specified position.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/string-prev-grapheme-cluster-break
```

</section>

<section class="usage">

## Usage

```javascript
var prevGraphemeClusterBreak = require( '@stdlib/string-prev-grapheme-cluster-break' );
```

#### prevGraphemeClusterBreak( string\[, fromIndex] )

Returns the previous extended grapheme cluster break in a string before a specified position.

```javascript
var out = prevGraphemeClusterBreak( 'last man standing' );
// returns 15
```

By default, the last extended grapheme cluster break in the string is returned. For the previous extended grapheme cluster break before a specified position in the string, provide a `fromIndex`.

```javascript
var out = prevGraphemeClusterBreak( 'last man standing', 4 );
// returns 3
```

</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 `string` is an empty string, the function returns `-1` irrespective of `fromIndex`.
-   If there is no extended grapheme cluster break before `fromIndex`, the function returns `-1`.
-   Note that `fromIndex` does **not** refer to a visual character position, but to an index in the ordered sequence of [UTF-16][utf-16] code units.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var prevGraphemeClusterBreak = require( '@stdlib/string-prev-grapheme-cluster-break' );

console.log( prevGraphemeClusterBreak( 'last man standing', 4 ) );
// => 3

console.log( prevGraphemeClusterBreak( 'presidential election', 8 ) );
// => 7

console.log( prevGraphemeClusterBreak( 'अनुच्छेद', 2 ) );
// => 0

console.log( prevGraphemeClusterBreak( '🌷', 1 ) );
// => -1
```

</section>

<!-- /.examples -->

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



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<section class="related">

## See Also

-   <span class="package-name">[`@stdlib/string-prev-grapheme-cluster-break-cli`][@stdlib/string-prev-grapheme-cluster-break-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-num-grapheme-clusters`][@stdlib/string/num-grapheme-clusters]</span><span class="delimiter">: </span><span class="description">return the number of grapheme clusters in a string.</span>
-   <span class="package-name">[`@stdlib/string-next-grapheme-cluster-break`][@stdlib/string/next-grapheme-cluster-break]</span><span class="delimiter">: </span><span class="description">return the next extended grapheme cluster break in a string after a specified position.</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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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[@stdlib/string-prev-grapheme-cluster-break]: https://github.com/stdlib-js/string-prev-grapheme-cluster-break/tree/main

[umd]: https://github.com/umdjs/umd
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[deno-url]: https://github.com/stdlib-js/string-prev-grapheme-cluster-break/tree/deno
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[@stdlib/string/num-grapheme-clusters]: https://www.npmjs.com/package/@stdlib/string-num-grapheme-clusters

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