JS-LocalDate-Plus

js-localdate-plus is a JS library inspired by LocalDate. Fix bugs and add some new temporal features.

Installation

Add js-localdate-plus as a dependency to package.json:

$ npm install --save js-localdate-plus

Or via bower

$ bower install js-localdate-plus

then

import LocalDate from 'js-localdate-plus'

New Feature

Add Years/Months with Gap Day

var date_with_gap = (new LocalDate(2001, 1, 31)).addMonthsWithGap(1);
// date_with_gap will be 2001-3-3

WithGap means: When adding years/months, if the original day of the month is greater than the number of days in the final month, the final month will change to the next month and the final day will be the first day plus gap days in the final month. It's similar to the conception of Carry in arithmetic.

Fix bugs from LocalDate

addYears() and substractYears() do not check whether a year is a leap year. The issue with details.

Original Usage from LocalDate

Creating a LocalDate object

var today = new LocalDate();
var epoch = new LocalDate(1970, 1, 1);

A LocalDate can be instantiated with a String, Date or Julian day.

new LocalDate('1984-05-02');
new LocalDate(new Date(1984, 4, 2));
new LocalDate(2445823);

The basic value of LocalDate tracks the Julian Day. Think of it like the Unix epoch, number of (milli)seconds since 1.1.1970, except for days since 4714 BC.

The Julian Day is the integer assigned to a whole solar day in the Julian day count starting from noon Greenwich Mean Time, with Julian day number 0 assigned to the day starting at noon on January 1, 4713 BC, proleptic Julian calendar (November 24, 4714 BC, in the proleptic Gregorian calendar).

For whole (integer) Julian days the time is assumed to be 12:00 GMT. LocalDate doesn't keep time or timezones, so the Julian day value is not representative of the point in time (noon), rather the whole solar day.

Converters

today.toDate();
epoch.toString();
today.toJulianDay(); //same as today.valueOf()

Clone

var another = today.clone();

Getters & Setters

Setters return new LocalDate instances, they do not modify the existing instance;

today.getYear();
today.getMonth();
today.getDay();
 
var past = today.setYear(2000).setMonth(2).setDay(29);

Comparators

You can compare two LocalDate objects, or a LocalDate to a String.

birth.isBefore(today); // true
today.isAfter(past); // true
today.equals(new Date); // true
 
past.isBefore('1923-02-22'); // false

Utility

There are lots of utility methods.

today.getDayOfWeek();
today.getDayOfYear();
 
birth.isLeapYear();
birth.isValid();
 
today.lengthOfMonth();
today.lengthOfYear();

Add & Subtract

You can add or subtract years, months and days.

var again = another.addMonths(22).subtractDays(10);

When adding months, if the original day of the month is greater than the number of days in the final month, the day will become the last day in the calculated month.