npm package: @stdlib/assert-is-leap-year-cli
Description: Test if a value corresponds to a leap year in the Gregorian calendar.
Author: The Stdlib Authors
Latest version: 0.2.3

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# isLeapYear

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

> Test if a value corresponds to a [leap year][leap-year] in the [Gregorian calendar][gregorian-calendar].

A [leap year][leap-year] is defined as any year which is exactly divisible by `4`, except for years which are exactly divisible by `100` and not by `400`. In this definition, `100` corresponds to years marking a new century, and `400` corresponds to the length of the _leap cycle_.











<section class="cli">



<section class="installation">

## Installation

To use as a general utility, install the CLI package globally

```bash
npm install -g @stdlib/assert-is-leap-year-cli
```

</section>

<!-- CLI usage documentation. -->

<section class="usage">

## Usage

```text
Usage: is-leap-year [options] [<year>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
```

</section>

<!-- /.usage -->

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

<section class="notes">

## Notes

-   If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.

    ```bash
    # Not escaped...
    $ echo -n $'1993\n1992' | is-leap-year --split /\r?\n/
    # Escaped...
    $ echo -n $'1993\n1992' | is-leap-year --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

```bash
$ is-leap-year
<boolean>

$ is-leap-year 1993
false
```

To use as a [standard stream][standard-streams],

```bash
$ echo -n 1992 | is-leap-year
true
```

By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.

```bash
$ echo -n '1992\t1993' | is-leap-year --split '\t'
true
false
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

## See Also

-   <span class="package-name">[`@stdlib/assert-is-leap-year`][@stdlib/assert-is-leap-year]</span><span class="delimiter">: </span><span class="description">test if a value corresponds to a leap year in the Gregorian calendar.</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>

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[npm-image]: http://img.shields.io/npm/v/@stdlib/assert-is-leap-year-cli.svg
[npm-url]: https://npmjs.org/package/@stdlib/assert-is-leap-year-cli

[test-image]: https://github.com/stdlib-js/assert-is-leap-year/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/assert-is-leap-year/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/assert-is-leap-year/main.svg
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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/assert-is-leap-year#cli
[cli-url]: https://github.com/stdlib-js/assert-is-leap-year/tree/cli
[@stdlib/assert-is-leap-year]: https://www.npmjs.com/package/@stdlib/assert-is-leap-year

[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/assert-is-leap-year/tree/deno
[deno-readme]: https://github.com/stdlib-js/assert-is-leap-year/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/assert-is-leap-year/tree/umd
[umd-readme]: https://github.com/stdlib-js/assert-is-leap-year/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/assert-is-leap-year/tree/esm
[esm-readme]: https://github.com/stdlib-js/assert-is-leap-year/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/assert-is-leap-year/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-leap-year/main/LICENSE

[leap-year]: https://en.wikipedia.org/wiki/Leap_year

[gregorian-calendar]: https://en.wikipedia.org/wiki/Gregorian_calendar

[date-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date

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

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

</section>

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