npm package: @stdlib/time-iso-weeks-in-year
Description: Determine the number of ISO weeks in a year according to the Gregorian calendar.
Author: The Stdlib Authors
Latest version: 0.2.3

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# isoWeeksInYear

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

> Determine the number of [ISO weeks][iso-week-date] in a year according to the [Gregorian calendar][gregorian-calendar].

<section class="installation">

## Installation

```bash
npm install @stdlib/time-iso-weeks-in-year
```

</section>

<section class="usage">

## Usage

```javascript
var isoWeeksInYear = require( '@stdlib/time-iso-weeks-in-year' );
```

#### isoWeeksInYear( \[value] )

Returns the number of [ISO weeks][iso-week-date] in a year according to the [Gregorian calendar][gregorian-calendar].

```javascript
var num = isoWeeksInYear();
// returns <number>
```

By default, the function returns the number of [ISO weeks][iso-week-date] in the current year (according to local time). To determine the number of [ISO weeks][iso-week-date] for a particular year, provide either a year or a [`Date`][date-object] object.

```javascript
var num = isoWeeksInYear( new Date() );
// returns <number>

num = isoWeeksInYear( 2015 );
// returns 53

num = isoWeeksInYear( 2017 );
// returns 52
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var isoWeeksInYear = require( '@stdlib/time-iso-weeks-in-year' );

var v;
var i;

for ( i = 0; i < 2021; i++ ) {
    v = isoWeeksInYear( i );
    console.log( 'The year %d has %d ISO weeks.', i, v );
}
```

</section>

<!-- /.examples -->



<!-- 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/time-iso-weeks-in-year-cli`][@stdlib/time-iso-weeks-in-year-cli]</span><span class="delimiter">: </span><span class="description">CLI package for use as a command-line utility.</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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<section class="links">

[@stdlib/time-iso-weeks-in-year-cli]: https://www.npmjs.com/package/@stdlib/time-iso-weeks-in-year-cli

[npm-image]: http://img.shields.io/npm/v/@stdlib/time-iso-weeks-in-year.svg
[npm-url]: https://npmjs.org/package/@stdlib/time-iso-weeks-in-year

[test-image]: https://github.com/stdlib-js/time-iso-weeks-in-year/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/time-iso-weeks-in-year/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/time-iso-weeks-in-year/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/time-iso-weeks-in-year?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/time-iso-weeks-in-year#cli
[cli-url]: https://github.com/stdlib-js/time-iso-weeks-in-year/tree/cli
[@stdlib/time-iso-weeks-in-year]: https://github.com/stdlib-js/time-iso-weeks-in-year/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/time-iso-weeks-in-year/tree/deno
[deno-readme]: https://github.com/stdlib-js/time-iso-weeks-in-year/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/time-iso-weeks-in-year/tree/umd
[umd-readme]: https://github.com/stdlib-js/time-iso-weeks-in-year/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/time-iso-weeks-in-year/tree/esm
[esm-readme]: https://github.com/stdlib-js/time-iso-weeks-in-year/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/time-iso-weeks-in-year/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/time-iso-weeks-in-year/main/LICENSE

[iso-week-date]: https://en.wikipedia.org/wiki/ISO_week_date

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

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

</section>

<!-- /.links -->