npm package: @stdlib/time-day-of-year
Description: Determine the day of the year.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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</details>

# dayOfYear

[![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 day of the year.

<section class="installation">

## Installation

```bash
npm install @stdlib/time-day-of-year
```

</section>

<section class="usage">

## Usage

```javascript
var dayOfYear = require( '@stdlib/time-day-of-year' );
```

#### dayOfYear( \[month\[, day, year]] )

Returns the day of the year.

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

By default, the function returns the day of the year for the current date (according to local time). To determine the day of the year for a particular day, provide `month`, `day`, and `year` arguments.

```javascript
var num = dayOfYear( 12, 31, 2016 );
// returns 366

num = dayOfYear( 12, 31, 2017 );
// returns 365
```

A `month` may be either a month's integer value, three letter abbreviation, or full name (case insensitive).

```javascript
var num = dayOfYear( 12, 31, 2016 );
// returns 366

num = dayOfYear( 'dec', 31, 2016 );
// returns 366

num = dayOfYear( 'december', 31, 2016 );
// returns 366
```

The function also supports providing a [`Date`][date-object] object.

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

</section>

<!-- /.usage -->

<section class="examples">

## Examples

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

```javascript
var dayOfYear = require( '@stdlib/time-day-of-year' );

var v;
var i;

for ( i = 0; i < 2021; i++ ) {
    v = dayOfYear( 'Dec', 31, i );
    console.log( 'In the year %d, December 31 is day number %d.', 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-day-of-year-cli`][@stdlib/time-day-of-year-cli]</span><span class="delimiter">: </span><span class="description">CLI package for use as a command-line utility.</span>
-   <span class="package-name">[`@stdlib/time-day-of-quarter`][@stdlib/time/day-of-quarter]</span><span class="delimiter">: </span><span class="description">determine the day of the quarter.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<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>

<!-- /.stdlib -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[@stdlib/time-day-of-year-cli]: https://www.npmjs.com/package/@stdlib/time-day-of-year-cli

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

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

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/time-day-of-year/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/time-day-of-year?branch=main

<!--

[dependencies-image]: https://img.shields.io/david/stdlib-js/time-day-of-year.svg
[dependencies-url]: https://david-dm.org/stdlib-js/time-day-of-year/main

-->

[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com

[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-day-of-year#cli
[cli-url]: https://github.com/stdlib-js/time-day-of-year/tree/cli
[@stdlib/time-day-of-year]: https://github.com/stdlib-js/time-day-of-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-day-of-year/tree/deno
[deno-readme]: https://github.com/stdlib-js/time-day-of-year/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/time-day-of-year/tree/umd
[umd-readme]: https://github.com/stdlib-js/time-day-of-year/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/time-day-of-year/tree/esm
[esm-readme]: https://github.com/stdlib-js/time-day-of-year/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/time-day-of-year/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/time-day-of-year/main/LICENSE

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

<!-- <related-links> -->

[@stdlib/time/day-of-quarter]: https://www.npmjs.com/package/@stdlib/time-day-of-quarter

<!-- </related-links> -->

</section>

<!-- /.links -->