Develop Reference

How to correctly calculate difference in days between 2 dates with DST change?

I have a task to get days difference between 2 dates. My solution is like here https://stackoverflow.com/a/543152/3917754 just I use Math.ceil instead of Math.round - cause 1 day and something is more than 1 day.
It was fine until I got dates between DST change. For example:
In my timezone DST change was on 30 Oct.
So when I'm trying to find days diff between dates 20 Oct and 10 Nov in result I get 23 instead of 22.
There are solution how to identify DST date but is it good solution to add/substract 1 day if date is/isn't dst?
function datediff(toDate, fromDate) {
const millisecondsPerDay = 1000 * 60 * 60 * 24; // milliseconds in day
fromDate.setHours(0, 0, 0, 0); // Start just after midnight
toDate.setHours(23, 59, 59, 999); // End just before midnight
const millisBetween = toDate.getTime() - fromDate.getTime();
var days = Math.ceil(millisBetween / millisecondsPerDay);
return days;
}
var startDate = new Date('2022-10-20');
var endDate = new Date('2022-11-10');
console.log('From date: ', startDate);
console.log('To date: ', endDate);
console.log(datediff(endDate, startDate));

How to get unix timestamp from tomorrow nodejs

I want to get Unix timestamp (time in seconds) from tomorrow.
I have tried the following with no success:
var d = new Date();
d.setDate(d.getDay() - 1);
d.setHours(0, 0, 0);
d.setMilliseconds(0);
console.log(d/1000|0)
How would I fix the above?

Just modified your code and it works fine
var d = new Date();
d.setDate(d.getDate() + 1);
d.setHours(0, 0, 0);
d.setMilliseconds(0);
console.log(d)
>> Sun Apr 21 2019 00:00:00 GMT+0530 (India Standard Time)
Hope this will work for you

This should do it.
Copied directly from https://javascript.info/task/get-seconds-to-tomorrow
function getSecondsToTomorrow() {
let now = new Date();
// tomorrow date
let tomorrow = new Date(now.getFullYear(), now.getMonth(), now.getDate()+1);
let diff = tomorrow - now; // difference in ms
return Math.round(diff / 1000); // convert to seconds
}
console.log(getSecondsToTomorrow());

you could use a third party library like moment js which makes your life alot easier
momentjs

You can use a unix timestamp and add 24*60*60*1000 (same as 86400000) to the current time's timestamp. You can then pass that to new Date() like this:
24 = hours
60 = minutes
60 = seconds
1000 = converts the result to milliseconds
// Current timestamp
const now = Date.now()
// Get 24 hours from now
const next = new Date(now + (24*60*60*1000))
// Create tomorrow's date
const t = new Date(next.getFullYear(), next.getMonth(), next.getDate())
// Subtract the two and divide by 1000
console.log(Math.round((t.getTime() - now) / 1000), 'seconds until tomorrow')

Setting a set date with javascript

Using a countdown plugin but I think I'm setting the date and time wrong.
Code:
var clock;
$(document).ready(function() {
// Grab the current date
var currentDate = new Date();
// Set some date in the future. In this case, it's always Jan 1
var futureDate = new Date(2016,10,27, 10,00,00);
// Calculate the difference in seconds between the future and current date
var diff = futureDate.getTime() / 1000 - currentDate.getTime() / 1000;
// Instantiate a coutdown FlipClock
clock = $('.clock').FlipClock(diff, {
clockFace: 'DailyCounter',
countdown: true
});
});
I'm attempting this:
var futureDate = new Date(2016,10,27, 10,00,00);
Which is 27th October 2016 at 10am
Coding up 52 days though so I must be doing something wrong

Which is 27th October 2016 at 10am
That's where you're going wrong. Months in JavaScript are 0-indexed (January is 0, December is 11), the 10th month is actually November.
var futureDate = new Date(2016,9,27,10,00,00);

Javascript adding days to a Date

Hi I am trying to create a variable today that is the current date today. I am trying to add 106 days to it which works successfully. Then I am trying to create a second variable today2 and subtract 31 days from the 'today' variable (current date + 106 -31). This part is not working. This is what it is giving me...
Thu Mar 28 11:52:21 EDT 2013
Tue Nov 27 11:52:21 EST 2012
The second line is not 31 days before the first line. Can someone help me correct this?
Feel free to play with my jsfiddle http://jsfiddle.net/fjhxW/
<div id="current"></div>
<div id="current2"></div>
<div id="current3"></div>
var today = new Date();
var today2 = new Date();
today.setDate(today.getDate() + 106);
today2.setDate(today.getDate() - 31);
var dd = today.getDate();
var mm = today.getMonth(); //January is 0!
var yy = today.getFullYear();
document.getElementById('current').innerHTML = today;
document.getElementById('current2').innerHTML = today2;

it's Xmas time so I give the answer just to copy/paste:
var oneDay = 24 * 60 * 60 * 1000, // 24h
today = new Date().getTime(), // in ms
firstDate,
secondDate;
firstDate = new Date(today + 106 * oneDay);
secondDate = new Date(firstDate.getTime() - 31 * oneDay);

try datejs:
Date.parse('t - 31 d'); // today - 31 days
Date.today().add(106).days().add(-31).days();

You cannot pass a negative number to setDate. setDate is used to set the date to set the absolute day, not relative days.
From the docs:
If the parameter you specify is outside of the expected range, setDate attempts to update the date information in the Date object accordingly. For example, if you use 0 for dayValue, the date will be set to the last day of the previous month.

A mathemathical solution:
Add 75 days to your current day (106 - 31), then add 31 days to that date. Change the order in what you are showing both dates on your code.
Why go forward and backward when you can always go forward?

How can I add 1 day to current date?

I have a current Date object that needs to be incremented by one day using the JavaScript Date object. I have the following code in place:
var ds = stringFormat("{day} {date} {month} {year}", {
day: companyname.i18n.translate("day", language)[date.getUTCDay()],
date: date.getUTCDate(),
month: companyname.i18n.translate("month", language)[date.getUTCMonth()],
year: date.getUTCFullYear()
});
How can I add one day to it?
I've added +1 to getUTCDay() and getUTCDate() but it doesn't display 'Sunday'
for day, which I am expecting to happen.

To add one day to a date object:
var date = new Date();
// add a day
date.setDate(date.getDate() + 1);

In my humble opinion the best way is to just add a full day in milliseconds, depending on how you factor your code it can mess up if you are on the last day of the month.
For example Feb 28 or march 31.
Here is an example of how I would do it:
var current = new Date(); //'Mar 11 2015' current.getTime() = 1426060964567
var followingDay = new Date(current.getTime() + 86400000); // + 1 day in ms
followingDay.toLocaleDateString();
Imho this insures accuracy
Here is another example. I do not like that. It can work for you but not as clean as example above.
var today = new Date('12/31/2015');
var tomorrow = new Date(today);
tomorrow.setDate(today.getDate()+1);
tomorrow.toLocaleDateString();
Imho this === 'POOP'
So some of you have had gripes about my millisecond approach because of day light savings time. So I'm going to bash this out. First, Some countries and states do not have Day light savings time. Second Adding exactly 24 hours is a full day. If the date number does not change once a year but then gets fixed 6 months later I don't see a problem there. But for the purpose of being definite and having to deal with allot the evil Date() I have thought this through and now thoroughly hate Date. So this is my new Approach.
var dd = new Date(); // or any date and time you care about
var dateArray = dd.toISOString().split('T')[0].split('-').concat( dd.toISOString().split('T')[1].split(':') );
// ["2016", "07", "04", "00", "17", "58.849Z"] at Z
Now for the fun part!
var date = {
day: dateArray[2],
month: dateArray[1],
year: dateArray[0],
hour: dateArray[3],
minutes: dateArray[4],
seconds:dateArray[5].split('.')[0],
milliseconds: dateArray[5].split('.')[1].replace('Z','')
}
Now we have our Official Valid international Date Object clearly written out at Zulu meridian.
Now to change the date
dd.setDate(dd.getDate()+1); // this gives you one full calendar date forward
tomorrow.setDate(dd.getTime() + 86400000);// this gives your 24 hours into the future. do what you want with it.

If you want add a day (24 hours) to current datetime you can add milliseconds like this:
new Date(Date.now() + ( 3600 * 1000 * 24))

int days = 1;
var newDate = new Date(Date.now() + days*24*60*60*1000);
CodePen
var days = 2;
var newDate = new Date(Date.now()+days*24*60*60*1000);
document.write('Today: <em>');
document.write(new Date());
document.write('</em><br/> New: <strong>');
document.write(newDate);

Inspired by jpmottin in this question, here's the one line code:
var dateStr = '2019-01-01';
var days = 1;
var result = new Date(new Date(dateStr).setDate(new Date(dateStr).getDate() + days));
document.write('Date: ', result); // Wed Jan 02 2019 09:00:00 GMT+0900 (Japan Standard Time)
document.write('<br />');
document.write('Trimmed Date: ', result.toISOString().substr(0, 10)); // 2019-01-02
Hope this helps

simply you can do this
var date = new Date();
date.setDate(date.getDate() + 1);
console.log(date);
now the date will be the date of tomorrow. here you can add or deduct the number of days as you wish.

This is function you can use to add a given day to a current date in javascript.
function addDayToCurrentDate(days){
let currentDate = new Date()
return new Date(currentDate.setDate(currentDate.getDate() + days))
}
// current date = Sun Oct 02 2021 13:07:46 GMT+0200 (South Africa Standard Time)
// days = 2
console.log(addDayToCurrentDate(2))
// Mon Oct 04 2021 13:08:18 GMT+0200 (South Africa Standard Time)

// Function gets date and count days to add to passed date
function addDays(dateTime, count_days = 0){
return new Date(new Date(dateTime).setDate(dateTime.getDate() + count_days));
}
// Create some date
const today = new Date("2022-02-19T00:00:00Z");
// Add some days to date
const tomorrow = addDays(today, 1);
// Result
console.log("Tomorrow => ", new Date(tomorrow).toISOString());
// 2022-02-20T00:00:00.000Z

We can get date of the day after today by using timedelta with numOfDays specified as 1 below.
from datetime import date, timedelta
tomorrow = date.today() + timedelta(days=1)

currentDay = '2019-12-06';
currentDay = new Date(currentDay).add(Date.DAY, +1).format('Y-m-d');