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https://github.com/stdlib-js/string-code-point-at
Return a Unicode code point from a string at a specified position.
https://github.com/stdlib-js/string-code-point-at
astral code javascript node node-js nodejs point pt stdlib str string surrogate unicode utf-16 utf16 util utilities utility utils
Last synced: about 1 month ago
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Return a Unicode code point from a string at a specified position.
- Host: GitHub
- URL: https://github.com/stdlib-js/string-code-point-at
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-14T13:32:29.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-12-01T03:17:54.000Z (about 2 months ago)
- Last Synced: 2024-12-01T04:23:22.738Z (about 2 months ago)
- Topics: astral, code, javascript, node, node-js, nodejs, point, pt, stdlib, str, string, surrogate, unicode, utf-16, utf16, util, utilities, utility, utils
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 832 KB
- Stars: 2
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
Awesome Lists containing this project
README
About stdlib...
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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!
# codePointAt
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Return a Unicode [code point][code-point] from a string at a specified position.
## Installation
```bash
npm install @stdlib/string-code-point-at
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
- To use as a general utility for the command line, install the corresponding [CLI package][cli-section] globally.
The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
## Usage
```javascript
var codePointAt = require( '@stdlib/string-code-point-at' );
```
#### codePointAt( string, position\[, backward] )
Returns a Unicode [code point][code-point] from a string at a specified position.
```javascript
var out = codePointAt( 'last man standing', 4 );
// returns 32
```
The function supports providing a `backward` argument for performing backward iteration for low surrogates.
```javascript
var out = codePointAt( '🌷', 1, true );
// returns 127799
```
The function supports providing a negative `position`.
```javascript
var out = codePointAt( 'last man standing', -13 );
// returns 32
```
## Notes
This function differs from [`String.prototype.codePointAt`][mdn-string-codepointat] in the following ways:
- The function supports providing a negative `position`. If provided a negative `position`, the function determines the string position relative to the end of the string.
- The function supports providing a `backward` argument for performing backward iteration for low surrogates. [`String.prototype.codePointAt`][mdn-string-codepointat] simply returns the low surrogate value if no [UTF-16][utf-16] surrogate pair begins at the specified position. If invoked with `backward` set to `true`, this function will return the code point after aggregating with the preceding high surrogate, if the specified position does not mark the start of a surrogate pair.
- The function raises an exception if provided a `position` which exceeds the bounds of the input string.
## Examples
```javascript
var codePointAt = require( '@stdlib/string-code-point-at' );
var v = codePointAt( 'last man standing', 4 );
// returns 32
v = codePointAt( 'presidential election', 8, true );
// returns 116
v = codePointAt( 'अनुच्छेद', 2 );
// returns 2369
v = codePointAt( '🌷', 1, true );
// returns 127799
```
* * *
## CLI
## Installation
To use as a general utility, install the CLI package globally
```bash
npm install -g @stdlib/string-code-point-at-cli
```
### Usage
```text
Usage: code-point-at [options] --pos= []
Options:
-h, --help Print this message.
-V, --version Print the package version.
-b, --backward Backward iteration for low surrogates.
--pos index Position in string.
```
### Examples
```bash
$ code-point-at --pos=2 अनुच्छेद
2369
```
To use as a [standard stream][standard-streams],
```bash
$ echo -n 'अनुच्छेद' | code-point-at --pos=2
2369
```
* * *
## See Also
- [`@stdlib/string-from-code-point`][@stdlib/string/from-code-point]: create a string from a sequence of Unicode code points.
* * *
## 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 © 2016-2024. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/string-code-point-at.svg
[npm-url]: https://npmjs.org/package/@stdlib/string-code-point-at
[test-image]: https://github.com/stdlib-js/string-code-point-at/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/string-code-point-at/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/string-code-point-at/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/string-code-point-at?branch=main
[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im
[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-code-point-at#cli
[cli-url]: https://github.com/stdlib-js/string-code-point-at/tree/cli
[@stdlib/string-code-point-at]: https://github.com/stdlib-js/string-code-point-at/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-code-point-at/tree/deno
[deno-readme]: https://github.com/stdlib-js/string-code-point-at/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/string-code-point-at/tree/umd
[umd-readme]: https://github.com/stdlib-js/string-code-point-at/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/string-code-point-at/tree/esm
[esm-readme]: https://github.com/stdlib-js/string-code-point-at/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/string-code-point-at/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/string-code-point-at/main/LICENSE
[code-point]: https://en.wikipedia.org/wiki/Code_point
[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
[mdn-string-codepointat]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt
[utf-16]: https://en.wikipedia.org/wiki/UTF-16
[@stdlib/string/from-code-point]: https://github.com/stdlib-js/string-from-code-point