@stdlib/assert-is-leap-year

Test if a value corresponds to a leap year in the Gregorian calendar.

Usage no npm install needed!

<script type="module">
  import stdlibAssertIsLeapYear from 'https://cdn.skypack.dev/@stdlib/assert-is-leap-year';
</script>

README

isLeapYear

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Test if a value corresponds to a leap year in the Gregorian calendar.

A 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.

Installation

npm install @stdlib/assert-is-leap-year

Usage

var isLeapYear = require( '@stdlib/assert-is-leap-year' );

isLeapYear( [value] )

Tests if a value corresponds to a leap year in the Gregorian calendar.

var bool = isLeapYear();
// returns <boolean>

bool = isLeapYear( new Date() );
// returns <boolean>

bool = isLeapYear( 2000 );
// returns true

bool = isLeapYear( 2017 );
// returns false

Notes

  • If not provided any arguments, the function returns a boolean indicating if the current year (according to local time) is a leap year.

  • If provided a value which is neither an integer value nor a Date, the function always returns false.

    var bool = isLeapYear( '2016' );
// returns false

bool = isLeapYear( null );
// returns false

Examples

var isLeapYear = require( '@stdlib/assert-is-leap-year' );

var bool;
var i;

for ( i = 0; i < 2021; i++ ) {
    bool = isLeapYear( i );
    console.log( 'The year %d %s a leap year.', i, ( bool ) ? 'is' : 'is not' );
}

CLI

Installation

To use the module as a general utility, install the module globally

npm install -g @stdlib/assert-is-leap-year

Usage

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

Options:

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

Examples

$ is-leap-year
<boolean>

$ is-leap-year 1993
false

To use as a standard stream,

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

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.

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License

See LICENSE.

Copyright

Copyright © 2016-2021. The Stdlib Authors.