dayOfYear

Determine the day of the year.

Installation

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

Alternatively,

To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
If you are using Deno, visit the deno branch (see README for usage intructions).
For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).
To use as a general utility for the command line, install the corresponding CLI package globally.

The branches.md 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

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

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

Returns the day of the year.

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.

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).

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 object.

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

Examples

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 );
}

CLI

Installation

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

npm install -g @stdlib/time-day-of-year-cli

Usage

Usage: day-of-year [options] [<month> <day> <year>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.

Examples

$ day-of-year
<number>

For a specific date,

$ day-of-year 12 31 2016
366

Notice

This package is part of 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, see the main project repository.