Date Wrapper

A simple library to wrap js dates with extra functionality, easy validation, immutability, chainability, and string formatting

• No external dependencies

Usage

Available as npm package including cjs, esm, umd, and iife
npm install date-wrapper

In browser using script tags
date-wrapper.iife.js date-wrapper.iife.min.js

Features and Examples

Create an object using strings or standard js Dates

dateWrapper(dateInput, is_ddmmFormat?) => dateWrapper Object

const D = dateWrapper;  // Alias
 
D(new Date());     // js Date()
 
D('2019/01/01');   // yyyy/mm/dd
D('2019/1/1');     // yyyy/m/d
 
// mm/dd/yyyy format
D('01/01/2019');         // mm/dd/yyyy
D('1/1/2019');           // m/d/yyyy
// pass optional parameter to create using dd/mm/yyyy format
D('31/12/2019', true);   // dd/mm/yyyy
D('1/1/2019', true);     // d/m/yyyy
 
// separator can be / or -
D('01-01-2019');

---

Invalid dates will return undefined, making for easy string validation

D('13/01/2019');  // undefined       
D('01/32/2019');  // undefined
D('02/29/2019');  // undefined
                  // (leap year)
D('02/29/2020');  // Sat Feb 29 2020 00:00:00

---

Setting the time

.setTime(hours, minutes, seconds, milliseconds) => dateWrapper object 
// returns undefined if arg out of range: (h 0-23, m 0-59, s 0-59, ms 0-999)

D('01/01/2019');                          // Tue Jan 01 2019 00:00:00              
D('01/01/2019').setTime(8, 30, 59, 999);  // Tue Jan 01 2019 08:30:59
D('01/01/2019').setTime(8);               // Tue Jan 01 2019 08:00:00

---

Adding to or Subtracting from the date

.addDays(days) => dateWrapper object
.addYears(years) => dateWrapper object

D('01/01/2019').addDays(9);      // Thu Jan 10 2019 00:00:00
D('01/01/2019').addDays(-1);     // Mon Dec 31 2018 00:00:00
D('01/01/2019').addYears(1);     // Wed Jan 01 2020 00:00:00
D('01/01/2019').addYears(-19);   // Sat Jan 01 2000 00:00:00

---

Adding to or Subtracting from the time

.addTime(hours, minutes, seconds, milliseconds) => dateWrapper object

D('01/01/2019').addTime(25, 10, -20, 0);  // Wed Jan 02 2019 01:09:40
D('01/01/2019').addTime(0, -1);           // Mon Dec 31 2018 23:59:00

---

Immutability and chaining

// all operations create a new copy
var today = D('01/01/2019');               // Tue Jan 01 2019 00:00:00
// chain operations
var dt = today.addDays(32).addYears(1);
var tomorrow = today.addDays(1);           // Wed Jan 02 2019 00:00:00
// today remains unchanged
today;                                     // Tue Jan 01 2019 00:00:00
var jsDate = today.toDate();               
jsDate.setDate(jsDate.getDate() + 10);     // Tue Jan 11 2019 00:00:00
// today remains unchanged
today;                                     // Tue Jan 01 2019 00:00:00

---

Comparing dates with or without the time component

.equals(dateOrDateWrapper, compareIncludingTime?) => boolean
.isOnOrBefore(dateOrDateWrapper, compareIncludingTime?) => boolean
.isBefore(dateOrDateWrapper, compareIncludingTime?) => boolean
.isOnOrAfter(dateOrDateWrapper, compareIncludingTime?) => boolean
.isAfter(dateOrDateWrapper, compareIncludingTime?) => boolean

// comparison functions accept DateWrapper objects or js Dates
var isSame = D(inputStr).equals(D('1/1/2019'));
var isSame = D(inputStr).equals(new Date(2019, 0, 1));
 
// examples
var D_now = D(new Date());              // Fri Mar 08 2019 20:46:23
var D_userInput = D(getUserInput());    // Fri Mar 08 2019 00:00:00              
 
// compare dates ignoring their time
D_userInput.equals(D_now);              // true
// compare dates including their time
D_userInput.equals(D_now, true);        // false
 
D_userInput.isOnOrAfter(D_now);         // true
D_userInput.isOnOrAfter(D_now, true);   // false
D_userInput.isOnOrBefore(D_now);        // true
D_userInput.isOnOrBefore(D_now, true);  // true
D_userInput.isAfter(D_now);             // false
D_userInput.isAfter(D_now, true);       // false
D_userInput.isBefore(D_now);            // false
D_userInput.isBefore(D_now, true);      // true

---

Timespan between two dates

.from(dateOrDateWrapper) => { 
  days: number, 
  hours: number, 
  minutes: number, 
  seconds: number, 
  ms: number 
}

var timespan = D(tomorrow).from(D(today));  
// { days: 1, hours: 0, minutes: 0, seconds: 0, ms: 0 }
var timespan = D(today).from(D(tomorrow));  
// { days: -1, hours: 0, minutes: 0, seconds: 0, ms: 0 }

---

Getting first and last days of the current month or year

.firstOfMonth() => DateWrapper object
.lastOfMonth() => DateWrapper object
.firstOfYear() => DateWrapper object
.lastOfYear() => DateWrapper object

D('05/15/2019').firstOfMonth();  // Wed May 01 2019 00:00:00
D('05/15/2019').lastOfMonth();   // Fri May 31 2019 00:00:00
D('05/15/2019').firstOfYear();   // Tue Jan 01 2019 00:00:00
D('05/15/2019').lastOfYear();    // Tue Dec 31 2019 00:00:00

---

String and js Date representation

.toDate() => Date
.toString() => string   // the default js Date.toString() output

---

Custom formatting using toString() parameter

.toString(formatString) => string

code	example		code	example		code	example		code	example
yyyy	2019		M	1		d	1		H	16
yy	19		MM	01		dd	01		HH	16
			MMM	Jan		ddd	Tue		h	4
			MMMM	January		dddd	Tuesday		hh	04
									mm	29
									ss	59
									fff	050
									tt	PM

var date = D('01/01/2019').setTime(16, 29, 59, 50);
date.toString('MM/dd/yy');                           // '01/01/19'
date.toString('dddd MMMM d, yyyy hh:mm:ss.fff tt');  // 'Tuesday January 1, 2019 04:29:59.050 PM'
var timestamp = date.toString('yyyyMMdd-HHmmss');    // '20190101-162959'