npm package: @stdlib/string-utf16-to-utf8-array
Description: Convert a UTF-16 encoded string to an array of integers using UTF-8 encoding.
Author: The Stdlib Authors
Latest version: 0.2.3

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# UTF-16 to UTF-8

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

> Convert a [UTF-16][utf-16] encoded string to an array of integers using [UTF-8][utf-8] encoding.

<!-- 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-utf16-to-utf8-array
```

</section>

<section class="usage">

## Usage

```javascript
var utf16ToUTF8Array = require( '@stdlib/string-utf16-to-utf8-array' );
```

#### utf16ToUTF8Array( str )

Converts a [UTF-16][utf-16] encoded string to an `array` of integers using [UTF-8][utf-8] encoding.

```javascript
var out = utf16ToUTF8Array( '☃' );
// returns [ 226, 152, 131 ]
```

</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

-   [UTF-16][utf-16] encoding uses one 16-bit unit for non-surrogates (`U+0000` to `U+D7FF` and `U+E000` to `U+FFFF`).

-   [UTF-16][utf-16] encoding uses two 16-bit units (surrogate pairs) for `U+10000` to `U+10FFFF` and encodes `U+10000-U+10FFFF` by subtracting `0x10000` from the code point, expressing the result as a 20-bit binary, and splitting the 20 bits of `0x0-0xFFFFF` as upper and lower 10-bits. The respective 10-bits are stored in two 16-bit words: a **high** and a **low** surrogate.

-   [UTF-8][utf-8] is defined to encode code points in one to four bytes, depending on the number of significant bits in the numerical value of the code point. Encoding uses the following byte sequences:

    ```text
    0x00000000 - 0x0000007F:
        0xxxxxxx

    0x00000080 - 0x000007FF:
        110xxxxx 10xxxxxx

    0x00000800 - 0x0000FFFF:
        1110xxxx 10xxxxxx 10xxxxxx

    0x00010000 - 0x001FFFFF:
        11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
    ```

    where an `x` represents a code point bit. Only the shortest possible multi-byte sequence which can represent a code point is used.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var utf16ToUTF8Array = require( '@stdlib/string-utf16-to-utf8-array' );

var values;
var out;
var i;

values = [
    'Ladies + Gentlemen',
    'An encoded string!',
    'Dogs, Cats & Mice',
    '☃',
    'æ',
    '𐐷'
];
for ( i = 0; i < values.length; i++ ) {
    out = utf16ToUTF8Array( values[ i ] );
    console.log( '%s: %s', values[ i ], out.join( ',' ) );
}
```

</section>

<!-- /.examples -->

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* * *

## 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].

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/string-utf16-to-utf8-array/main/LICENSE

[utf-8]: https://en.wikipedia.org/wiki/UTF-8

[utf-16]: https://en.wikipedia.org/wiki/UTF-16

</section>

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