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Playwright Current Date +1 Day [duplicate]

I have a date with the format Sun May 11,2014. How can I convert it to 2014-05-11 using JavaScript?
function taskDate(dateMilli) {
var d = (new Date(dateMilli) + '').split(' ');
d[2] = d[2] + ',';
return [d[0], d[1], d[2], d[3]].join(' ');
}
var datemilli = Date.parse('Sun May 11,2014');
console.log(taskDate(datemilli));
The code above gives me the same date format, sun may 11,2014. How can I fix this?

Just leverage the built-in toISOString method that brings your date to the ISO 8601 format:
let yourDate = new Date()
yourDate.toISOString().split('T')[0]
Where yourDate is your date object.
Edit: #exbuddha wrote this to handle time zone in the comments:
const offset = yourDate.getTimezoneOffset()
yourDate = new Date(yourDate.getTime() - (offset*60*1000))
return yourDate.toISOString().split('T')[0]

You can do:
function formatDate(date) {
var d = new Date(date),
month = '' + (d.getMonth() + 1),
day = '' + d.getDate(),
year = d.getFullYear();
if (month.length < 2)
month = '0' + month;
if (day.length < 2)
day = '0' + day;
return [year, month, day].join('-');
}
console.log(formatDate('Sun May 11,2014'));
Usage example:
console.log(formatDate('Sun May 11,2014'));
Output:
2014-05-11
Demo on JSFiddle: http://jsfiddle.net/abdulrauf6182012/2Frm3/

I use this way to get the date in format yyyy-mm-dd :)
var todayDate = new Date().toISOString().slice(0, 10);
console.log(todayDate);

2020 ANSWER
You can use the native .toLocaleDateString() function which supports several useful params like locale (to select a format like MM/DD/YYYY or YYYY/MM/DD), timezone (to convert the date) and formats details options (eg: 1 vs 01 vs January).
Examples
const testCases = [
new Date().toLocaleDateString(), // 8/19/2020
new Date().toLocaleString(undefined, {year: 'numeric', month: '2-digit', day: '2-digit', weekday:"long", hour: '2-digit', hour12: false, minute:'2-digit', second:'2-digit'}),
new Date().toLocaleDateString('en-US', {year: 'numeric', month: '2-digit', day: '2-digit'}), // 08/19/2020 (month and day with two digits)
new Date().toLocaleDateString('en-ZA'), // 2020/08/19 (year/month/day) notice the different locale
new Date().toLocaleDateString('en-CA'), // 2020-08-19 (year-month-day) notice the different locale
new Date().toLocaleString("en-US", {timeZone: "America/New_York"}), // 8/19/2020, 9:29:51 AM. (date and time in a specific timezone)
new Date().toLocaleString("en-US", {hour: '2-digit', hour12: false, timeZone: "America/New_York"}), // 09 (just the hour)
]
for (const testData of testCases) {
console.log(testData)
}
Notice that sometimes to output a date in your specific desire format, you have to find a compatible locale with that format.
You can find the locale examples here: https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_tolocalestring_date_all
Please notice that locale just change the format, if you want to transform a specific date to a specific country or city time equivalent then you need to use the timezone param.

The simplest way to convert your date to the yyyy-mm-dd format, is to do this:
var date = new Date("Sun May 11,2014");
var dateString = new Date(date.getTime() - (date.getTimezoneOffset() * 60000 ))
.toISOString()
.split("T")[0];
How it works:
new Date("Sun May 11,2014") converts the string "Sun May 11,2014" to a date object that represents the time Sun May 11 2014 00:00:00 in a timezone based on current locale (host system settings)
new Date(date.getTime() - (date.getTimezoneOffset() * 60000 )) converts your date to a date object that corresponds with the time Sun May 11 2014 00:00:00 in UTC (standard time) by subtracting the time zone offset
.toISOString() converts the date object to an ISO 8601 string 2014-05-11T00:00:00.000Z
.split("T") splits the string to array ["2014-05-11", "00:00:00.000Z"]
[0] takes the first element of that array
Demo
var date = new Date("Sun May 11,2014");
var dateString = new Date(date.getTime() - (date.getTimezoneOffset() * 60000 ))
.toISOString()
.split("T")[0];
console.log(dateString);
Note :
The first part of the code (new Date(...)) may need to be tweaked a bit if your input format is different from that of the OP. As mikeypie
pointed out in the comments, if the date string is already in the expected output format and the local timezone is west of UTC, then new Date('2022-05-18') results in 2022-05-17. And a user's locale (eg. MM/DD/YYYY vs DD-MM-YYYY) may also impact how a date is parsed by new Date(...). So do some proper testing if you want to use this code for different input formats.

A combination of some of the answers:
var d = new Date(date);
date = [
d.getFullYear(),
('0' + (d.getMonth() + 1)).slice(-2),
('0' + d.getDate()).slice(-2)
].join('-');

format = function date2str(x, y) {
var z = {
M: x.getMonth() + 1,
d: x.getDate(),
h: x.getHours(),
m: x.getMinutes(),
s: x.getSeconds()
};
y = y.replace(/(M+|d+|h+|m+|s+)/g, function(v) {
return ((v.length > 1 ? "0" : "") + z[v.slice(-1)]).slice(-2)
});
return y.replace(/(y+)/g, function(v) {
return x.getFullYear().toString().slice(-v.length)
});
}
Result:
format(new Date('Sun May 11,2014'), 'yyyy-MM-dd')
"2014-05-11

If you don't have anything against using libraries, you could just use the Moments.js library like so:
var now = new Date();
var dateString = moment(now).format('YYYY-MM-DD');
var dateStringWithTime = moment(now).format('YYYY-MM-DD HH:mm:ss');
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>

You can use toLocaleDateString('fr-CA') on Date object
console.log(new Date('Sun May 11,2014').toLocaleDateString('fr-CA'));
Also I found out that those locales give right result from this locales list List of All Locales and Their Short Codes?
'en-CA'
'fr-CA'
'lt-LT'
'sv-FI'
'sv-SE'
var localesList = ["af-ZA",
"am-ET",
"ar-AE",
"ar-BH",
"ar-DZ",
"ar-EG",
"ar-IQ",
"ar-JO",
"ar-KW",
"ar-LB",
"ar-LY",
"ar-MA",
"arn-CL",
"ar-OM",
"ar-QA",
"ar-SA",
"ar-SY",
"ar-TN",
"ar-YE",
"as-IN",
"az-Cyrl-AZ",
"az-Latn-AZ",
"ba-RU",
"be-BY",
"bg-BG",
"bn-BD",
"bn-IN",
"bo-CN",
"br-FR",
"bs-Cyrl-BA",
"bs-Latn-BA",
"ca-ES",
"co-FR",
"cs-CZ",
"cy-GB",
"da-DK",
"de-AT",
"de-CH",
"de-DE",
"de-LI",
"de-LU",
"dsb-DE",
"dv-MV",
"el-GR",
"en-029",
"en-AU",
"en-BZ",
"en-CA",
"en-GB",
"en-IE",
"en-IN",
"en-JM",
"en-MY",
"en-NZ",
"en-PH",
"en-SG",
"en-TT",
"en-US",
"en-ZA",
"en-ZW",
"es-AR",
"es-BO",
"es-CL",
"es-CO",
"es-CR",
"es-DO",
"es-EC",
"es-ES",
"es-GT",
"es-HN",
"es-MX",
"es-NI",
"es-PA",
"es-PE",
"es-PR",
"es-PY",
"es-SV",
"es-US",
"es-UY",
"es-VE",
"et-EE",
"eu-ES",
"fa-IR",
"fi-FI",
"fil-PH",
"fo-FO",
"fr-BE",
"fr-CA",
"fr-CH",
"fr-FR",
"fr-LU",
"fr-MC",
"fy-NL",
"ga-IE",
"gd-GB",
"gl-ES",
"gsw-FR",
"gu-IN",
"ha-Latn-NG",
"he-IL",
"hi-IN",
"hr-BA",
"hr-HR",
"hsb-DE",
"hu-HU",
"hy-AM",
"id-ID",
"ig-NG",
"ii-CN",
"is-IS",
"it-CH",
"it-IT",
"iu-Cans-CA",
"iu-Latn-CA",
"ja-JP",
"ka-GE",
"kk-KZ",
"kl-GL",
"km-KH",
"kn-IN",
"kok-IN",
"ko-KR",
"ky-KG",
"lb-LU",
"lo-LA",
"lt-LT",
"lv-LV",
"mi-NZ",
"mk-MK",
"ml-IN",
"mn-MN",
"mn-Mong-CN",
"moh-CA",
"mr-IN",
"ms-BN",
"ms-MY",
"mt-MT",
"nb-NO",
"ne-NP",
"nl-BE",
"nl-NL",
"nn-NO",
"nso-ZA",
"oc-FR",
"or-IN",
"pa-IN",
"pl-PL",
"prs-AF",
"ps-AF",
"pt-BR",
"pt-PT",
"qut-GT",
"quz-BO",
"quz-EC",
"quz-PE",
"rm-CH",
"ro-RO",
"ru-RU",
"rw-RW",
"sah-RU",
"sa-IN",
"se-FI",
"se-NO",
"se-SE",
"si-LK",
"sk-SK",
"sl-SI",
"sma-NO",
"sma-SE",
"smj-NO",
"smj-SE",
"smn-FI",
"sms-FI",
"sq-AL",
"sr-Cyrl-BA",
"sr-Cyrl-CS",
"sr-Cyrl-ME",
"sr-Cyrl-RS",
"sr-Latn-BA",
"sr-Latn-CS",
"sr-Latn-ME",
"sr-Latn-RS",
"sv-FI",
"sv-SE",
"sw-KE",
"syr-SY",
"ta-IN",
"te-IN",
"tg-Cyrl-TJ",
"th-TH",
"tk-TM",
"tn-ZA",
"tr-TR",
"tt-RU",
"tzm-Latn-DZ",
"ug-CN",
"uk-UA",
"ur-PK",
"uz-Cyrl-UZ",
"uz-Latn-UZ",
"vi-VN",
"wo-SN",
"xh-ZA",
"yo-NG",
"zh-CN",
"zh-HK",
"zh-MO",
"zh-SG",
"zh-TW",
"zu-ZA"
];
localesList.forEach(lcl => {
if ("2014-05-11" === new Date('Sun May 11,2014').toLocaleDateString(lcl)) {
console.log(lcl, new Date('Sun May 11,2014').toLocaleDateString(lcl));
}
});

The 2021 solution using Intl.
The new Intl Object is now supported on all browsers.
You can choose the format by choosing a "locale" that uses the required format.
The Swedish locale uses the format "yyyy-mm-dd":
// Create a date
const date = new Date(2021, 10, 28);
// Create a formatter using the "sv-SE" locale
const dateFormatter = Intl.DateTimeFormat('sv-SE');
// Use the formatter to format the date
console.log(dateFormatter.format(date)); // "2021-11-28"
Downsides of using Intl:
You cannot "unformat" or "parse" strings using this method
You have to search for the required format (for instance on Wikipedia) and cannot use a format-string like "yyyy-mm-dd"

Simply use this:
var date = new Date('1970-01-01'); // Or your date here
console.log((date.getMonth() + 1) + '/' + date.getDate() + '/' + date.getFullYear());
Simple and sweet ;)

Shortest
.toJSON().slice(0,10);
var d = new Date('Sun May 11,2014' +' UTC'); // Parse as UTC
let str = d.toJSON().slice(0,10); // Show as UTC
console.log(str);

toISOString() assumes your date is local time and converts it to UTC. You will get an incorrect date string.
The following method should return what you need.
Date.prototype.yyyymmdd = function() {
var yyyy = this.getFullYear().toString();
var mm = (this.getMonth()+1).toString(); // getMonth() is zero-based
var dd = this.getDate().toString();
return yyyy + '-' + (mm[1]?mm:"0"+mm[0]) + '-' + (dd[1]?dd:"0"+dd[0]);
};
Source: https://blog.justin.kelly.org.au/simple-javascript-function-to-format-the-date-as-yyyy-mm-dd/

In the most of cases (no time zone handling) this is enough:
date.toISOString().substring(0,10)
Example
var date = new Date();
console.log(date.toISOString()); // 2022-07-04T07:14:08.925Z
console.log(date.toISOString().substring(0,10)); // 2022-07-04

Retrieve year, month, and day, and then put them together. Straight, simple, and accurate.
function formatDate(date) {
var year = date.getFullYear().toString();
var month = (date.getMonth() + 101).toString().substring(1);
var day = (date.getDate() + 100).toString().substring(1);
return year + "-" + month + "-" + day;
}
//Usage example:
alert(formatDate(new Date()));

new Date('Tue Nov 01 2022 22:14:53 GMT-0300').toLocaleDateString('en-CA');
new Date().toLocaleDateString('pt-br').split( '/' ).reverse( ).join( '-' );
or
new Date().toISOString().split('T')[0]
new Date('23/03/2020'.split('/').reverse().join('-')).toISOString()
new Date('23/03/2020'.split('/').reverse().join('-')).toISOString().split('T')[0]
Try this!

When ES2018 rolls around (works in chrome) you can simply regex it
(new Date())
.toISOString()
.replace(
/^(?<year>\d+)-(?<month>\d+)-(?<day>\d+)T.*$/,
'$<year>-$<month>-$<day>'
)
2020-07-14
Or if you'd like something pretty versatile with no libraries whatsoever
(new Date())
.toISOString()
.match(
/^(?<yyyy>\d\d(?<yy>\d\d))-(?<mm>0?(?<m>\d+))-(?<dd>0?(?<d>\d+))T(?<HH>0?(?<H>\d+)):(?<MM>0?(?<M>\d+)):(?<SSS>(?<SS>0?(?<S>\d+))\.\d+)(?<timezone>[A-Z][\dA-Z.-:]*)$/
)
.groups
Which results in extracting the following
{
H: "8"
HH: "08"
M: "45"
MM: "45"
S: "42"
SS: "42"
SSS: "42.855"
d: "14"
dd: "14"
m: "7"
mm: "07"
timezone: "Z"
yy: "20"
yyyy: "2020"
}
Which you can use like so with replace(..., '$<d>/$<m>/\'$<yy> # $<H>:$<MM>') as at the top instead of .match(...).groups to get
14/7/'20 # 8:45

const formatDate = d => [
d.getFullYear(),
(d.getMonth() + 1).toString().padStart(2, '0'),
d.getDate().toString().padStart(2, '0')
].join('-');
You can make use of padstart.
padStart(n, '0') ensures that a minimum of n characters are in a string and prepends it with '0's until that length is reached.
join('-') concatenates an array, adding '-' symbol between every elements.
getMonth() starts at 0 hence the +1.

To consider the timezone also, this one-liner should be good without any library:
new Date().toLocaleString("en-IN", {timeZone: "Asia/Kolkata"}).split(',')[0]

You can try this: https://www.npmjs.com/package/timesolver
npm i timesolver
Use it in your code:
const timeSolver = require('timeSolver');
const date = new Date();
const dateString = timeSolver.getString(date, "YYYY-MM-DD");
You can get the date string by using this method:
getString

I suggest using something like formatDate-js instead of trying to replicate it every time. Just use a library that supports all the major strftime actions.
new Date().format("%Y-%m-%d")

Unfortunately, JavaScript's Date object has many pitfalls. Any solution based on Date's builtin toISOString has to mess with the timezone, as discussed in some other answers to this question. The clean solution to represent an ISO-8601 date (without time) is given by Temporal.PlainDate from the Temporal proposal. As of February 2021, you have to choose the workaround that works best for you.
use Date with vanilla string concatenation
Assuming that your internal representation is based on Date, you can perform manual string concatenation. The following code avoids some of Date's pitfalls (timezone, zero-based month, missing 2-digit formatting), but there might be other issues.
function vanillaToDateOnlyIso8601() {
// month May has zero-based index 4
const date = new Date(2014, 4, 11);
const yyyy = date.getFullYear();
const mm = String(date.getMonth() + 1).padStart(2, "0"); // month is zero-based
const dd = String(date.getDate()).padStart(2, "0");
if (yyyy < 1583) {
// TODO: decide how to support dates before 1583
throw new Error(`dates before year 1583 are not supported`);
}
const formatted = `${yyyy}-${mm}-${dd}`;
console.log("vanilla", formatted);
}
use Date with helper library (e.g. formatISO from date-fns)
This is a popular approach, but you are still forced to handle a calendar date as a Date, which represents
a single moment in time in a platform-independent format
The following code should get the job done, though:
import { formatISO } from "date-fns";
function dateFnsToDateOnlyIso8601() {
// month May has zero-based index 4
const date = new Date(2014, 4, 11);
const formatted = formatISO(date, { representation: "date" });
console.log("date-fns", formatted);
}
find a library that properly represents dates and times
I wish there was a clean and battle-tested library that brings its own well-designed date–time representations. A promising candidate for the task in this question was LocalDate from #js-joda/core, but the library is less active than, say, date-fns. When playing around with some example code, I also had some issues after adding the optional #js-joda/timezone.
However, the core functionality works and looks very clean to me:
import { LocalDate, Month } from "#js-joda/core";
function jodaDateOnlyIso8601() {
const someDay = LocalDate.of(2014, Month.MAY, 11);
const formatted = someDay.toString();
console.log("joda", formatted);
}
experiment with the Temporal-proposal polyfill
This is not recommended for production, but you can import the future if you wish:
import { Temporal } from "proposal-temporal";
function temporalDateOnlyIso8601() {
// yep, month is one-based here (as of Feb 2021)
const plainDate = new Temporal.PlainDate(2014, 5, 11);
const formatted = plainDate.toString();
console.log("proposal-temporal", formatted);
}

Here is one way to do it:
var date = Date.parse('Sun May 11,2014');
function format(date) {
date = new Date(date);
var day = ('0' + date.getDate()).slice(-2);
var month = ('0' + (date.getMonth() + 1)).slice(-2);
var year = date.getFullYear();
return year + '-' + month + '-' + day;
}
console.log(format(date));

Date.js is great for this.
require("datejs")
(new Date()).toString("yyyy-MM-dd")

Simply Retrieve year, month, and day, and then put them together.
function dateFormat(date) {
const day = date.getDate();
const month = date.getMonth() + 1;
const year = date.getFullYear();
return `${year}-${month}-${day}`;
}
console.log(dateFormat(new Date()));

None of these answers quite satisfied me. I wanted a cross-platform solution that gave me the day in the local timezone without using any external libraries.
This is what I came up with:
function localDay(time) {
var minutesOffset = time.getTimezoneOffset()
var millisecondsOffset = minutesOffset*60*1000
var local = new Date(time - millisecondsOffset)
return local.toISOString().substr(0, 10)
}
That should return the day of the date, in YYYY-MM-DD format, in the timezone the date references.
So for example, localDay(new Date("2017-08-24T03:29:22.099Z")) will return "2017-08-23" even though it's already the 24th at UTC.
You'll need to polyfill Date.prototype.toISOString for it to work in Internet Explorer 8, but it should be supported everywhere else.

A few of the previous answer were OK, but they weren't very flexible. I wanted something that could really handle more edge cases, so I took #orangleliu 's answer and expanded on it. https://jsfiddle.net/8904cmLd/1/
function DateToString(inDate, formatString) {
// Written by m1m1k 2018-04-05
// Validate that we're working with a date
if(!isValidDate(inDate))
{
inDate = new Date(inDate);
}
// See the jsFiddle for extra code to be able to use DateToString('Sun May 11,2014', 'USA');
//formatString = CountryCodeToDateFormat(formatString);
var dateObject = {
M: inDate.getMonth() + 1,
d: inDate.getDate(),
D: inDate.getDate(),
h: inDate.getHours(),
m: inDate.getMinutes(),
s: inDate.getSeconds(),
y: inDate.getFullYear(),
Y: inDate.getFullYear()
};
// Build Regex Dynamically based on the list above.
// It should end up with something like this: "/([Yy]+|M+|[Dd]+|h+|m+|s+)/g"
var dateMatchRegex = joinObj(dateObject, "+|") + "+";
var regEx = new RegExp(dateMatchRegex,"g");
formatString = formatString.replace(regEx, function(formatToken) {
var datePartValue = dateObject[formatToken.slice(-1)];
var tokenLength = formatToken.length;
// A conflict exists between specifying 'd' for no zero pad -> expand
// to '10' and specifying yy for just two year digits '01' instead
// of '2001'. One expands, the other contracts.
//
// So Constrict Years but Expand All Else
if (formatToken.indexOf('y') < 0 && formatToken.indexOf('Y') < 0)
{
// Expand single digit format token 'd' to
// multi digit value '10' when needed
var tokenLength = Math.max(formatToken.length, datePartValue.toString().length);
}
var zeroPad = (datePartValue.toString().length < formatToken.length ? "0".repeat(tokenLength) : "");
return (zeroPad + datePartValue).slice(-tokenLength);
});
return formatString;
}
Example usage:
DateToString('Sun May 11,2014', 'MM/DD/yy');
DateToString('Sun May 11,2014', 'yyyy.MM.dd');
DateToString(new Date('Sun Dec 11,2014'),'yy-M-d');

If you use momentjs, now they include a constant for that format YYYY-MM-DD:
date.format(moment.HTML5_FMT.DATE)

Yet another combination of the answers. Nicely readable, but a little lengthy.
function getCurrentDayTimestamp() {
const d = new Date();
return new Date(
Date.UTC(
d.getFullYear(),
d.getMonth(),
d.getDate(),
d.getHours(),
d.getMinutes(),
d.getSeconds()
)
// `toIsoString` returns something like "2017-08-22T08:32:32.847Z"
// and we want the first part ("2017-08-22")
).toISOString().slice(0, 10);
}

Reformatting a date string is fairly straightforward, e.g.
var s = 'Sun May 11,2014';
function reformatDate(s) {
function z(n){return ('0' + n).slice(-2)}
var months = [,'jan','feb','mar','apr','may','jun',
'jul','aug','sep','oct','nov','dec'];
var b = s.split(/\W+/);
return b[3] + '-' +
z(months.indexOf(b[1].substr(0,3).toLowerCase())) + '-' +
z(b[2]);
}
console.log(reformatDate(s));

Javascript: Get date string from raw date

I have another question on SO Unable to read date cell. This question is related to last question but more generic. How to convert Raw date, which represents number of days since 1st Jan 1900, to a javascript date type? [ Forget office365 ].
I have number of days elapsed since 1st Jan 1900. How can I get the date from it. For ex: I need a date after 42216 days, since 1st Jan 1900, How can I calculate that date? Answer is : 31-Jul-2015.

Try this:
(function(){
var date = new Date(1900,1,1);
var dayCount = 42216;
date.setDate(date.getDate() + dayCount)
console.log(date);
})()

Try this:
start = "01/01/1900"
newDate = start.split("/");
x = new Date(newDate[2]+"/"+newDate[1]+"/"+newDate[0]);
var numberOfDaysToAdd = 42216;
x.setDate(x.getDate() + parseInt(numberOfDaysToAdd));
var dd = x.getDate();
var mm = x.getMonth() + 1;
var yyyy = x.getFullYear();
var format = dd+'/'+mm+'/'+yyyy;
alert(format);
JSFIDDLE DEMO

Hope it help:
var dateStart= new Date('1900-01-01');
var afterDay=42216;
var newDay=new Date(dateStart.getTime() + afterDay*24*60*60*1000);
alert(newDay);

compare 2 dates by combining date and time

var dateStart = $('input[id=orderdate-0]').val();
var timeStart = $('input[id=ordertime-0]').val();
var dateEnd = $('input[id=orderdate-1]').val();
var timeEnd = $('input[id=orderime-1]').val();
var startDate = new Date(dateStart + " " + timeStart);
var endDate = new Date(dateEnd + " " + timeEnd);
startDate.getTime();
alert(startDate);
i am trying to combine dateStart which is '2013-12-11' and timeStart which is '11:00' and trying to generate date out of it. But i get alert like invalid date. Is there anything wrong in code.?

The Date constructor is very particular about the date string formats it accepts.
Examples:
Dec 25, 1995
Wed, 09 Aug 1995 00:00:00
2011-10-10T14:48:00 (JavaScript 1.8.5+)
There is another constructor that take in the individual components of the date. If you break up your date strings into components you can use the following:
new Date(year, month, day, hour, minute);

Use moment JS plugin http://momentjs.com/
It's a date library for parsing, validating, manipulating, and formatting dates.

That is not a valid format for the parse function, you can use this instead:
var arr = dateStart.split('-');
var timeArr = timeStart.split(':');
new Date(arr[0], arr[1] -1, arr[2], timeArr[0] -1, timeArr[1] -1);
Read this.
Live DEMO

How to add weeks to date using javascript?

Javascript definitely isn't my strongest point. I've been attempting this for a couple of hours now and seem to be getting stuck with date formatting somewhere.
I have a form where a user selected a date (dd/mm/yyyy) and then this date will be taken and 2 weeks will be added to it and then date will be copied to another form field.
My latest attempt below isn't even adding a date yet just copying the selected date in one form field to another, if I select '03/02/2012', it outputs 'Fri Mar 02 2012 00:00:00 GMT+0000 (GMT Standard Time)', so its outputting in American format as well as the full date. How to I get it to out put in the same format and add 2 weeks?
function LicenceToOccupy(acceptCompletionDate)
{
var date1 = new Date(acceptCompletionDate);
document.frmAccept.acceptLicence.value = date1;
}

You can do this :
const numWeeks = 2;
const now = new Date();
now.setDate(now.getDate() + numWeeks * 7);
or as a function
const addWeeksToDate = (dateObj,numberOfWeeks) => {
dateObj.setDate(dateObj.getDate()+ numberOfWeeks * 7);
return dateObj;
}
const numberOfWeeks = 2
console.log(addWeeksToDate(new Date(), 2).toISOString());
You can see the fiddle here.
According to the documentation in MDN
The setDate() method sets the day of the Date object relative to the beginning of the currently set month.

This might not answer the question per se, but one can find a solution with these formulas.
6.048e+8 = 1 week in milliseconds
Date.now() = Now in milliseconds
Date.now() + 6.048e+8 = 1 week from today
Date.now() + (6.048e+8 * 2) = 2 weeks from today
new Date( Date.now() + (6.048e+8 * 2) ) = Date Object for 2 weeks from today

You're assigning date1 to be a Date object which represents the string you pass it. What you're seeing in the acceptLicense value is the toString() representation of the date object (try alert(date1.toString()) to see this).
To output as you want, you'll have to use string concatenation and the various Date methods.
var formattedDate = date1.getDate() + '/' + (date1.getMonth() + 1) + '/' + date1.getFullYear();
In terms of adding 2 weeks, you should add 14 days to the current date;
date1.setDate(date.getDate() + 14);
... this will automatically handle the month increase etc.
In the end, you'll end up with;
var date1 = new Date(acceptCompletionDate);
date1.setDate(date1.getDate() + 14);
document.frmAccept.acceptLicence.value = date1.getDate() + '/' + (date1.getMonth() + 1) + '/' + date1.getFullYear();
N.B Months in JavaScript are 0-indexed (Jan = 0, Dec = 11), hence the +1 on the month.
Edit: To address your comment, you should construct date as follows instead, as the Date argument is supposed to be "A string representing an RFC2822 or ISO 8601 date." (see here).
var segments = acceptCompletionDate.split("/");
var date1 = new Date(segments[2], segments[1], segments[0]);

This should do what you're looking for.
function LicenceToOccupy(acceptCompletionDate)
{
var date1 = new Date(acceptCompletionDate);
date1.setDate(date1.getDate() + 14);
document.frmAccept.acceptLicence.value = date1.getDate() + '/' + (date1.getMonth() + 1) + '/' + date1.getFullYear();
}

To parse the specific dd/mm/yyyy format and increment days with 14 , you can do something like split the parts, and create the date object with y/m/d given specfically. (incrementing the days right away) Providing the separator is always -, the following should work:
function LicenceToOccupy(acceptCompletionDate)
{
var parts = acceptCompletionDate.split("/");
var date1 = new Date(parts[2], (parts[1] - 1), parseInt(parts[0]) + 14); //month 0 based, day: parse to int and increment 14 (2 weeks)
document.frmAccept.acceptLicence.value = date1.toLocaleDateString(); //if the d/m/y format is the local string, otherwise some cusom formatting needs to be done
}

date1.toLocaleDateString()
Thiswill return you date1 as a String in the client convention
To create a new date date2 with 2 weeks more (2weeks = 27246060 seconds):
var date2 = new Date(date1 + 60*60*24*7*2);

Calculate the Date based on Current Date and No of Days using Javascript/Jquery

I need a help..
I have a Current Date and No of days column.
When i enter number of days,i should add current date plus no of days entered.
For example,
todays date 5th jan + 20(no of days) = 25th Jan 2011 in another column.
Kindly help me.
Thanks in Advance.

Date.js is fantastic for this.
Date.today().add(5).days();

As you are learning JavaScript you may find the w3schools site useful for simple examples of objects and functions that are exposed and how they may be used.
http://www.w3schools.com/jsref/jsref_obj_date.asp
You can calculate the date as follows:
var d = new Date(); // Gets current date
var day = 86400000; // # milliseconds in a day
var numberOfDays = 20;
d.setTime(d.getTime() + (day*numberOfDays)); // Add the number of days in milliseconds
You can then use one of the various methods of displaying the date:
alert(d.toUTCString());

You could do something like
Date.today().add(X).days();
Where X is the number of days the user has entered.

You can add dates like this in js:
var someDate = new Date();
var numberOfDaysToAdd = 6;
someDate.setDate(someDate.getDate() + numberOfDaysToAdd);
var month = someDate.getMonth() + 1; //Add 1 because January is set to 0 and Dec is 11
var day = someDate.getDate();
var year = someDate.getFullYear();
document.write(month + "/" + day + "/" + year);
See this p.cambell's answer here: How to add number of days to today's date?