npm package: @stdlib/time-days-in-month
Description: Determine the number of days in a month.
Author: The Stdlib Authors
Latest version: 0.2.3

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# daysInMonth

[![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 days in a month.

<section class="installation">

## Installation

```bash
npm install @stdlib/time-days-in-month
```

</section>

<section class="usage">

## Usage

```javascript
var daysInMonth = require( '@stdlib/time-days-in-month' );
```

#### daysInMonth( \[month\[, year]] )

Returns the number of days in a month.

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

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

```javascript
var num = daysInMonth( 2 );
// returns <number>

num = daysInMonth( 2, 2016 );
// returns 29

num = daysInMonth( 2, 2017 );
// returns 28
```

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

```javascript
var num = daysInMonth( 2, 2016 );
// returns 29

num = daysInMonth( 'feb', 2016 );
// returns 29

num = daysInMonth( 'february', 2016 );
// returns 29
```

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

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

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   The function's return value is a generalization and does **not** take into account inaccuracies due to daylight savings conventions, crossing timezones, or other complications with time and dates.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var daysInMonth = require( '@stdlib/time-days-in-month' );

var v;
var i;

for ( i = 0; i < 2021; i++ ) {
    v = daysInMonth( 'feb', i );
    console.log( 'In the year %d, February has %d days.', 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-days-in-month-cli`][@stdlib/time-days-in-month-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-days-in-year`][@stdlib/time/days-in-year]</span><span class="delimiter">: </span><span class="description">determine the number of days in a year according to the Gregorian calendar.</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-days-in-month-cli]: https://www.npmjs.com/package/@stdlib/time-days-in-month-cli

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

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

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

<!--

[dependencies-image]: https://img.shields.io/david/stdlib-js/time-days-in-month.svg
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-->

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

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/time-days-in-month/main/LICENSE

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

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

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

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

</section>

<!-- /.links -->