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isLeapYear
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-yearAlternatively,
- To load the package in a website via a
scripttag without installation and bundlers, use the ES Module available on theesmbranch (see README). - If you are using Deno, visit the
denobranch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umdbranch (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 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 falseNotes
-
If not provided any
arguments, the function returns abooleanindicating if the current year (according to local time) is a leap year. -
If provided a
valuewhich is neither an integer value nor aDate, the function always returnsfalse.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 as a general utility, install the CLI package globally
npm install -g @stdlib/assert-is-leap-year-cliUsage
Usage: is-leap-year [options] [<year>]
Options:
-h, --help Print this message.
-V, --version Print the package version.
--split sep Delimiter for stdin data. Default: '/\\r?\\n/'.
Notes
-
If the split separator is a regular expression, ensure that the
splitoption is either properly escaped or enclosed in quotes.# Not escaped... $ echo -n $'1993\n1992' | is-leap-year --split /\r?\n/ # Escaped... $ echo -n $'1993\n1992' | is-leap-year --split /\\r?\\n/
-
The implementation ignores trailing delimiters.
Examples
$ is-leap-year
<boolean>
$ is-leap-year 1993
falseTo use as a standard stream,
$ echo -n 1992 | is-leap-year
trueBy default, when used as a standard stream, the implementation assumes newline-delimited data. To specify an alternative delimiter, set the split option.
$ echo -n '1992\t1993' | is-leap-year --split '\t'
true
falseNotice
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.
Community
License
See LICENSE.
Copyright
Copyright © 2016-2024. The Stdlib Authors.
