ChatGPT解决这个技术问题 Extra ChatGPT

Format JavaScript date as yyyy-mm-dd

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?

Really consider using a library like Moment.js. It will format in desired result :)
Why using a library when 5 line of code can do the work ? @Ankur
Related: What are valid Date Time Strings in JavaScript? Note that "Sun May 11,2014" is not a valid date string and parsing it might fail in some browsers.
@Black Mamba why use library when few line do trick

L
Lindauson

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]

BE CAREFUL with this method as it first converts to the date to UTC. If you are in a + timezone and your time portion is early in the day, then it could roll-back a day. Alternatively, if you're in a - timezone and your time portion is late in the day, then it could roll forward a day.
Try this instead: new Date(yourDateStr).toISOString().split('T')[0]
const offset = yourDate.getTimezoneOffset(); yourDate = new Date(yourDate.getTime() + (offset*60*1000)); yourDate.toISOString().split('T')[0] this should solve the issue of timezone
now.toISOString().substring(0,10); This is a cleaner alternative, since it reminds you that YYYY-MM-DD are the first ten characters of the complete iso format
Note: using the helpful solution commented by @mjwrazor, I had to subtract instead of add the offset to get the correct date (change the + (offset to a - (offset)
K
Kos

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/


Really multiple variable declarations in the same statement? stackoverflow.com/questions/694102/…
@Fuser97381 Multiple variable declarations in the same statement is more than just an aesthetic style preference. It is a dangerous practice. If you inadvertently fail add a comma after each declaration you end up creating global variables. Not something that should be encouraged on what may become the canonical answer to a question.
'use strict'; @bhspencer
Reformatting a date string should not depend on successful parsing of non-standard strings by the built-in parser. Given the OP format, it can be reformatted in less code without using a Date at all.
this works like a charm but I don't understand why javascript does not have a native solution for this... I mean, we are in 2020 and date is an important aspect to web apps.
R
Ruslan López

I use this way to get the date in format yyyy-mm-dd :)

var todayDate = new Date().toISOString().slice(0, 10); console.log(todayDate);


How do you handle the date switching by a day as mentioned here by @Luke_Baulch?
You can do this: var todayDate = new Date(); todayDate.setMinutes(todayDate.getMinutes() - todayDate.getTimezoneOffset()); todayDate.toISOString().slice(0,10); This should help avoid the UTC problem.
@FernandoAguilar One doubt though, how do we know we need to subtract the offset or add it?
var todayDate = new Date(2018, 3 - 1, 26); todayDate.toISOString().slice(0, 10); gives me "2018-03-25". On another system var todayDate = new Date(2018, 3 - 1, 26, 17, 0, 0); todayDate.toISOString().slice(0, 10); gives me "2018-03-27".
Doesn't always work. It sometimes subtracts a day due to UTC conversion.
C
Carson

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.


This still suffers from problems with timezones as it is based off UTC, so you still have to jump all the hoops of determining the offset and altering the date.
@TimHobbs you can set the timezone you want eg: ("timeZone: "America/New_York") and the date will be converted to that timezone.
For my case where I didn't need the time zones, new Date().toLocaleDateString('en-CA') was perfect
Can you format to yyyy/mm/dd in toLocaleDateString() ?
@JamesPoulose yes, you can do new Date().toLocaleDateString('en-ZA');
J
John Slegers

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);


No one else is aghast that this is the simplest way??
@JoeDevmon : I don't see how that's relevant here. The - (date.getTimezoneOffset() * 60000 ) bit should eliminate any timezone differences, including the impact of daylight savings time.
@JohnSlegers that's what I was thinking, but then I was still getting the day before in some cases. I refactored and your example works now. I must have had a weird date string or something. Thanks for sticking with it and pointing that out. +1 👍
I've searched high and low across SO and other sites to find the best way to deal with timezone issues with dates in JS, and hands down, this is by far the easiest and the best. Thank you!
It sad but it is simpliest way to format js date to string you need. I'm new in js, but in java it is 100 times easier to format date to any format. That is why was thinking there are easier way, but after I tried different solutions I choose this one. Thank you for your answer.
a
aqwsez

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('-');

I like the solution the best - easy to read, and does not rely on toISOString() and the potential timezone pitfalls with using that function.
this is the first one that doesn't make my brain hurt.
This fails in Chrome if the date string is already in the expected output format and the local timezone is west of UTC: d = new Date('2022-05-18') results in '2022-05-17'. That means that if the user's locale format is not '5/18/2022' this might also break.
A
AJP
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

I like the additional flexibility that this solution gives over the other answers to this question. I haven't thoroughly tested this, but for the format I desired (i.e. "yyyy-MM-dd hh:mm:ss"), it works just as expected.
You could eaaaaaaaasily avoid eval.
here's a version which avoids the eval and comments better jsfiddle.net/8904cmLd/2
I benefited from this response. I did replace that line with the eval statement to return ((v.length > 1 ? "0" : "") + z[v.slice(-1)]).slice(-2);
"H" should be capitalized, not "h" (small)
P
Peter Mortensen

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');


Cool solution, but its a 300kb package
Applied in react project: npm install moment --save import moment from 'moment'; const showEventDate = moment(your-date-here).format('YYYY-MM-DD; HH:mm A'); A pure solution for presenting date/time in any format. It gives local date-time with AM/PM and whatever you need just changing the format. Moment.js also provides easy date/time counting solution.
@theTradeCoder as Adam mentioned above the size of moment is pretty large (I think it is more like 67kb, but still) so you should consider that when evaluating the ease of use and utility of any dependency. There are smaller alternatives (day.js = 2kb).
Just an update about the moment.js library that - moment.js is already discontinued.
A
Aleksandr Belugin

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)); } });


Any idea why this works? Is ISO format just the default, or do these locales genuinely use that format? If it's the former I'd be concerned that it could change unexpectedly in the future.
THis is not working with NodeJS outside of browser.
@jymbob I think these locales genuinely use those formats. I've came to the same answer by looking at this Wikipedia page: en.wikipedia.org/wiki/Date_format_by_country
After 3 days, and trawling through too many SO javascript date questions, and trying to ask a new question (30 mins before closed as duplicate) here at last is an answer that is actually correct. I could weep.
Thanks for these code, this is really a better shortcut to obtain format in js render.
P
Peter Mortensen

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 ;)


padding is not there for 2 letter format. it'll show single digit if date or month is less than 10 that's why can't use this directly.
yess but that can be achived simply using javascript, its totaly upto your requirement i think so , isn't it ? @YatenderSingh
yeah correct but check the title of question "yyyy-mm-dd" format he wants :)
var old_date = new Date(date); var new_date = old_date.getFullYear() + '-' + (old_date.getMonth() + 1) + '-' + old_date.getDate()
K
Kamil Kiełczewski

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);


This doesn't work when the client is ahead of the UTC and the date in the UTC time is one day behind the current client date.
We don't need a screenshot for this if you are not in the 00+00 timezone: > d=new Date() ; d.setHours(0,30,0,0) ; d --> Sat Oct 09 2021 00:30:00 GMT+0100 (BST) ; d.toJSON() --> "2021-10-08T23:30:00.000Z"
P
Peter Mortensen

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/


L
Luo Jiong Hui

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()));


That's the correct one
H
Hendrik Jan

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"


L
Luca C.

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

note "date" should be a var date = new Date() before this line. Or, just new Date() .toISOString().substring(0,10);
P
Peter Mortensen

To consider the timezone also, this one-liner should be good without any library:

new Date().toLocaleString("en-IN", {timeZone: "Asia/Kolkata"}).split(',')[0]

Problem with this is that every locale will return different result. For example en-GB will return 20/12/2012 and ko-KR will return2012. 12. 20.. But format should be yyyy-mm-dd
P
Peter Mortensen

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

W
Williaan Lopes
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!


The second option might display the wrong date because it will display the data in UTC timezone.
H
Hashbrown

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

There are several simpler ways to butcher the toISOString string which were already posted before this one. For people who are willing to tolerate the potential inaccuracy of using toISOString, the sheer overhead and code bloat makes this a solution that no one should consider (the first snippet anyway).
Look, man, unless you're trying to reparse dates literally hundreds of thousands of times in a matter of seconds you're not going to see any difference at all, so I don't know where you get off calling it bloat. Like with any other novel answer added to an old, already-answered question; this provides the reader with choice, and maybe, knowledge ("gee, I didnt know regex could do that!"). The reader should know whether or not an answer is appropriate for their usecase, and you insult them.
I never mentioned performance so you can leave the argument about 100,000 iterations. My point is that earlier answers provided simpler techniques.
Yes, but not readable, or easily extensible. You called it bloat, which is literally code...that is perceived as unnecessarily long, slow, or otherwise wasteful of resources. SO is primarily for knowledge, so yes, even though the literal question has been answered, sometimes there are other angles that others (and at least already literally 3▲) find might useful! Imagine that. I don't play the "Fastest Gun In The West" game, so when you see me post a late answer, it is because I have something valuable to offer and I hope that you will acknowledge the care that I take. -some hypocrite
Nothing hypocritical going on here. I am very clear about how the first snippet is far less attractive than simply calling .slice(0,10). slice() is much more concise, direct, readable. I love regex but not for this question. See how I am not attacking you as a person? I am judging your answer to this question.
A
Ado Ren
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.


P
Peter Mortensen

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")

J
Julius

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);
}

Note that the NPM package proposal-temporal is deprecated and should not be used. Developers looking for Temporal polyfills should check github.com/tc39/proposal-temporal#polyfills to see the recommended list of polyfills, which as of today are @js-temporal/polyfill and temporal-polyfill
G
Gergo Erdosi

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));

P
Pang

Date.js is great for this.

require("datejs")
(new Date()).toString("yyyy-MM-dd")

P
Peter Mortensen

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.


Maybe worth noting that it will only give you 2017-08-23 if you're sufficiently behind UTC (e.g. in the US).
P
Peter Mortensen

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');

Nice clean & commented solution. Yet I'm skeptical about the first argument, which is silently replaced by a fresh new date if not recognized as a valid date. I'd rather put this "optionnal default value" as 2nd argument instead, and return some kind of exception (could be a simple "Invalid date format" returned string) in case the format isn't recognized, so that error appear clearly to the tester/user
S
Stefan Zhelyazkov

If you use momentjs, now they include a constant for that format YYYY-MM-DD:

date.format(moment.HTML5_FMT.DATE)

P
Peter Mortensen

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));


A
Andrei

function myYmd(D){ var pad = function(num) { var s = '0' + num; return s.substr(s.length - 2); } var Result = D.getFullYear() + '-' + pad((D.getMonth() + 1)) + '-' + pad(D.getDate()); return Result; } var datemilli = new Date('Sun May 11,2014'); document.write(myYmd(datemilli));


k
kadrian

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);
}