warera

A lightweight Javascript/Typescript library for mutual conversion Japanese Calendar Date and Gregorian Calendar Date

Documentation

npm i warera

Gregorian Calendar to Japanese Calendar

date.getJapaneseCalendarDate()

Example

const date = warera(new Date(2019, 4, 1)); // 2019-05-01

console.log(date.getJapaneseCalendarDate());
//  is return value as...
//
//  {
//      era: {
//          long: '令和',
//          short: 'R
//      },
//      year: 1,
//      month: 5,
//      day: 1
//  }

Japanese Calendar to Gregorian Calendar

getDate()

Example

const date = warera({era: 'R', year: 1, month: 5, day: 1});
// or
const date = warera({era: '令和', year: 1, month: 5, day: 1});

console.log(date.getDate())
// is return value as Date class (Wed May 01 2019 00:00:00 GMT+0900)

Formatter

date.format(pattern: string, replaceToGanForFirstYear: boolean);

Example

const date = warera({era: 'R', year: 1, month: 5, day: 1});
date.format('WWWkky年kkM月kkD日') // '令和元年五月一日'

Arguments

'pattern'

Input	Example	Description
YYYY	2019	Gregorian calendar 4 digit year
WWW	令和	Japanese calendar era (Full name of kanji)
W	R	Japanese calendar era (Alphabet)
kky	二十一	Japanese calendar year (Japanese numeral long)
ky	二一	Japanese calendar year (Japanese numeral short)
ddy	弐拾壱	Japanese calendar year (Japanese numeral long old char)
dy	弐壱	Japanese calendar year (Japanese numeral short old char)
yy	01	Japanese calendar year (Arabic numeral padded by 0)
y	1	Japanese calendar year (Arabic numeral)
kkM	二十一	Month (Japanese numeral long)
kM	二一	Month (Japanese numeral short)
ddM	弐拾壱	Month (Japanese numeral long old char)
dM	弐壱	Month (Japanese numeral short old char)
MM	01	Month (Arabic numeral padded by 0)
M	1	Month (Arabic numeral)
kkD	二十一	Day (Japanese numeral long)
kD	二一	Day (Japanese numeral short)
ddD	弐拾壱	Day (Japanese numeral long old char)
dD	弐壱	Day (Japanese numeral short old char)
DD	01	Day (Arabic numeral padded by 0)
D	1	Day (Arabic numeral)

'replaceToGanForFirstYear'

In Japan, the first year when the era begins is sometimes called the "元年".
"元年" meaning "first year".

When 'replaceToGanForFirstYear' true,

const date = warera({era: 'R', year: 1, month: 5, day: 1}, true);
date.format('WWWkky年kkM月kkD日') // '令和元年五月一日'

When false,

const date = warera({era: 'R', year: 1, month: 5, day: 1});
date.format('WWWkky年kkM月kkD日') // '令和一年五月一日'

What's 'warera' ?

'warera' is coined word by 'wareki' (meaning Japanese Calendar) and 'era'!