How to get current month number from date object - javascript

I am trying to compare the value of month number field month=6coming from my backend to the current month number. if the match is true 'do something' else do 'something else'.
I have tried making use of javascript Date() object and also moment():
var date = new Date();
var month = date.getMonth()+1;
Moment:
var month = moment().month("M");
This here is the function where the value of the current month is required
// get all Item usage on each item by month
const GroupedByMonth = Object.values(
data.reduce((acc, curr) => {
if (curr._id.month === month){
return (
(acc[curr._id.name] = {
month: curr._id.month,
name: curr._id.name,
totalAmountSold:
(acc[curr._id.name]?.totalAmountSold || 0) +
curr.totalAmountSold,
}),
acc
);
}
return acc;
}, {})
);
console.log(GroupedByMonth);
Object from backend :
{month: 6, name: "Cement", totalAmountSold: -17}
expected output should should read :
if (curr._id.month(6 coming from backend) === month(6 coming from date object){
in the case of true, the rest of the functions is performed
Non of the method i tried worked as expected. I need help in solving this problem


I don't quite understand what you mean by
Non of the method i tried worked as expected.
What have you tried so far? And what are the results?
That aside you can try something like this:
var today = new Date(); //Thu Jun 18 2020 10:17:04 GMT-0300
var month = ('0' + (today.getMonth() + 1)).slice(-2);
//Expected output of month: '06'
Make sure that what you are trying to compare matches in value and type, since you are using ===


function isDateMatched (monthNo) {
return new Date().getMonth() === monthNo;
}
console.log('5th month ', isDateMatched(5))
console.log('4th month ', isDateMatched(4))
Reference https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getMonth
Date.getMonth() returns current month no.
You can simply pass the monthNo you get from backend & pass it to isDateMatched function, it will return a Boolean i.e, true/false
Based on this result you can do your work.

Related

What is the source of this off-by-one error in a JavaScript date?

I am trying to write a function that will take a string like 07/2020 and then return whether it is more than three months away.
I have written a function isMoreThan3MonthsHence that I am reasonably sure works correctly:
const isMoreThan3MonthsHence = ({ utcYear, utcMonth },
now = new Date,
target = new Date(Date.UTC(utcYear, utcMonth)),
threeMonthsAway = new Date(now.valueOf()).setUTCMonth(now.getUTCMonth() + 3)) =>
(target > threeMonthsAway)
console.log(isMoreThan3MonthsHence({ utcYear: 2020, utcMonth: 7 })) // true (correct!)
The problem comes when I try to construct a Date object to use to populate the arguments for isMoreThan3MonthsHence.
const validate = (str,
[localMonth, localYear] = str.split('/'),
date = new Date(+localYear, (+localMonth)-1)) =>
isMoreThan3MonthsHence({ utcYear: date.getUTCFullYear(), utcMonth: date.getUTCMonth() })
// Note: input is one-based months
console.log(validate('07/2020')) // false (but should be true!)
I think the reason is that new-ing up a Date in validate without specifying the timezone will use the local timezone in effect at the supplied date, which will be BST (UTC+1).
Wed Jul 01 2020 00:00:00 GMT+0100 (British Summer Time)
This time is actually 2300hrs on June 30th in UTC. So the month is actually 5 in zero-based terms. But I don't want this behavior. I want it so specifying July actually means July in UTC.
How can I fix this?

It looks like you're mixing the usage of Date.UTC and not when instantiating dates. For example, if you use the following for your validate function:
const validate = (str,
[month, year] = str.split('/'),
date = new Date(Date.UTC(+year, (+month)-1))) =>
isMoreThan3MonthsHence({ utcYear: date.getUTCFullYear(), utcMonth: date.getUTCMonth() })
// Note: input is one-based months
console.log(validate('07/2020')) // Now true
It works as expected: JSFiddle
Removing the usage of Date.UTC altogether would perform the calculation in the user's local timezone, with any applicable daylight saving adjustment included. This could be seen as a valid approach, however would result in the behaviour you have described.
Note I've renamed the local prefixed variables based on feedback from Bergi. Using Date.UTC implies you're passing in UTC arguments.

Other than mixing UTC and local dates, the way you're adding 3 months will cause an incorrect response for dates like 31 March, where adding 3 months simply by incrementing the month number results in a date for 1 July. See Adding months to a Date in JavaScript.
So validate('07,2020') will return false if run on 31 March.
To fix that, when adding months, check that the updated date is still on the same day in the month, otherwise it's rolled over so set it to the last day of the previous month.
function validate(s) {
let testDate = addMonths(new Date(), 3);
let [m, y] = s.split(/\D/);
return testDate < new Date(y, m-1);
};
function addMonths(date, months) {
let d = date.getDate();
date.setMonth(date.getMonth() + +months);
// If rolled over to next month, set to last day of previous month
if (date.getDate() != d) {
date.setDate(0);
}
return date;
}
// Sample
console.log('On ' + new Date().toDateString() + ':');
['07/2020', '04/2020'].forEach(
s => console.log(s + ' - ' + validate(s))
);

Better way to get the current date for the input type "date" as a default value? [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)

You can use this function for better format and easy of use:
function convert(date) {
const d = Date.parse(date)
const date_obj = new Date(d)
return `${date_obj.getFullYear()}-${date_obj.toLocaleString("default", { month: "2-digit" })}-${date_obj.toLocaleString("default", { day: "2-digit"})}`
}
This function will format the month as 2-digit output as well as the days

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);
}

Check if time is the same with Moment.js

How to check if time is the same for Moment objects with different dates?
For example I have object like
const endDate = moment().add(30, 'days').endOf('day');
and I want to check if some moment object is endOf day.
private isEndOfDay(dateTime: string) {
const m = moment().endOf('day');
return m.isSame(dateTime, 'minute');
}
const receivedDateFormat: string = 'YYYY-MM-DD hh:mm:ss';
this.isEndOfDay(this.endDate.format(this.receivedDateFormat))
But for this case, when I pass "minute" parameter, it will check minute, hour, day, month and year... which isn't what I want to check.

The part of the documentation that explains that behaviour is
When including a second parameter, it will match all units equal or larger. Passing in month will check month and year. Passing in day will check day, month, and year.
So, if you just want to compare the minutes, you'll need to do something like
endDate.minute() === startDate.minute()
To compare the time only, format() the dates
endDate.format('HH:mm:ss') === startDate.format('HH:mm:ss')

To compare only time part you can set a given date (year, month and day) to your input.
Please note that passing 'minute' to isSame will ignore seconds.
Here a live sample:
function isEndOfDay(dateTime) {
let m = moment().endOf('day');
let m2 = moment(dateTime);
m2.set({
y: m.year(),
M: m.month(),
D: m.date()
});
return m.isSame(m2, 'minute');
}
var endDate = moment().add(30, 'days').endOf('day');
const receivedDateFormat = 'YYYY-MM-DD hh:mm:ss';
var ret = isEndOfDay(endDate.format(this.receivedDateFormat))
console.log(ret);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
Another way to to is checking only units that matter for you:
function isEndOfDay(dateTime) {
let m = moment().endOf('day');
let m2 = moment(dateTime);
if( m.hours() === m2.hours() &&
m.minutes() === m2.minutes() &&
m.seconds() === m2.seconds() ){
return true;
}
return false;
}
var endDate = moment().add(30, 'days').endOf('day');
const receivedDateFormat = 'YYYY-MM-DD hh:mm:ss';
var ret = isEndOfDay(endDate.format(this.receivedDateFormat))
console.log(ret);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
See Get + Set section of the docs to see how to get and set units of moment objects.

Javascript : date automatically increments by +1 value (Convert String to Date object)

I use Date() function to convert string to date object . The problem is , If i give Date("April , 31 ,2012") it will take it as May , 01 , 2012 (for the rest of the days its working) Please check my approach is correct from the code below.
function TestDate(objValue,strError){
var ret=true;
var frmdate=objValue.value;
var datesplit=frmdate.split("-");
var y =datesplit[0];
var m=datesplit[1];
var d=datesplit[2];
var testdate;
// Create date object using given input data
testdate = new Date(m+"/"+d+"/"+y);
alert("Created date"+testdate.toString());
var td=testdate.getDate();
var tm=testdate.getMonth()+1;
var ty =testdate.getFullYear();
alert(d+"="+td);
alert(m+"="+tm);
alert(y+"="+ty);
var valid=((d==td) && (m==tm) && (y==ty));
alert(valid);
if(valid == false)
{
ret =false;
}
return ret;
}

As sayed by #ajreal in comments, April has only 30 days.
The internal date object increments the month to have a valid date.

The code:
testdate = new Date(m+"/"+d+"/"+y);
is depends on non-standard, implementation specific parsing of the string. Far better to use the data you started with to create a date unambiguously:
testdate = new Date(y, m - 1, d);
As for validating a date, a simple function using an ISO8601 compliant date of format yyyy-mm-dd is:
function validateDate(dateString) {
var bits = dateString.split('-');
var date = new Date(bits[0], bits[1] - 1, bits[2]);
return date && date.getFullYear() == bits[0] && date.getDate() == bits[2];
}
That way if the string passed to the function is turned into a date, you can check that the date so created matches the input. If not, it wasn't valid and the function returns false. It also returns false if the string doesn't get turned into a date.

translate timestamp date of birth - in the name of the day

i'm trying to translate a birth date in the "name" of the day, like monday, tuesday, etc. but i have some doubts on how to do it, i thought first : take the two timestamps (date of birth and current timestamp) and then use a "modulo" like %7 , then with the "rest" of the modulo looking through an array of names. But, actually, the timestamp is not meant to be divided by a modulo isn't it? how would you do?
Thanks

You can get the UNIX Timestamp using valueOf() function where you can use modulo but you might try using easier API to get the day name from a date. I have taken the actual date of birth, say 14 April 1983 in a timestamp format. I get the monthly date value and month value form the actual DOB. I construct another date object with the monthly-date and month value and current year's value. Then I get the weekly day value (0-6 = Sun-Sat) from this date, and show the mapped day name from the array containing the names of the days.
var days = "Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday";
var actualDOB = "04/14/1983";
var date = new Date(new Date().getFullYear(), new Date(actualDOB).getMonth(), new Date(actualDOB).getDate());
alert("The day of the week this year for your birthday is : " + days.split(',')[date.getDay()] + " (" + date.toDateString() + ")");
Hope this helps.

If you have a real Date object, you can use the getDay() method of it in combination with an array of weekdays. Same goes for months. Here's a function to return the formatted actual birthday, the original day of birth and the day for the birthday this year:
function birthDAY(dat){
var result = {},
birthday = new Date(dat),
weekdays = 'sun,mon,tue,wedness,thurs,fri,satur'.split(','),
months = 'jan,feb,mar,apr,may,jun,jul,aug,sep,oct,nov,dec'.split(','),
dateFormatted = function(dateobj) {
return [
weekdays[dateobj.getDay()],'day',
', ', months[dateobj.getMonth()],
' ', dateobj.getDate(),
' ', dateobj.getFullYear()
].join('');
};
result.bdformatted = dateFormatted(birthday);
result.origbd = weekdays[birthday.getDay()]+'day';
birthday.setFullYear(new Date().getFullYear());
result.bdthisyear = weekdays[birthday.getDay()]+'day');
return result;
}
//usage
var bdObj = birthDAY('1973/11/02'); // <- your timestamp here
alert(bdObj.bdformatted); //=> friday, nov 2 1973
alert(bdObj.origbd); //=> friday
alert(bdObj.bdthisyear); //=> wednessday

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