Add to current date with javascript and have months roll over - javascript

I need to use basic javascript here and I'm not well versed with it.
I do not want to use jquery (although I would prefer it)
I need to get the current date via javascript, add 2 days to it, then display the new date (with the 2 additional days factored in). This means on the 30 or 31st of the month, the month needs to rollover as does the year on Dec 30/31.
Thanks to this question and Samuel Meadows I can get the current date. I can add 2 days no problem. But I can't work out how to get the months (and year) to rollover properly.
Samuel's code:
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();
if(dd<10){dd='0'+dd} if(mm<10){mm='0'+mm} var today = mm+'/'+dd+'/'+yyyy;
document.write(today);
Any assistance would be greatly appreciated.
Thanks!

The date object will take care of this for you:
var date = new Date("March 30, 2005"); // get an edge date
date.getMonth(); // 2, which is March minus 1
date.setDate( date.getDate() + 2); //Add two days
date.getMonth(); //Now shows 3, which is April minus 1

Convert the number of days to milliseconds, and then add them to the date in question http://jsfiddle.net/Mn5Wz/

Here is the code to add days to the current date
​var today = new Date();
console.log(addDate(today, 2));
function addDate(dateObject, numDays) {
dateObject.setDate(dateObject.getDate() + numDays);
return dateObject.toLocaleDateString();
}

Related

Error incrementing days to a specific date

I'm trying to increment one day to a given date. My code, inspired by this answer, looks like:
var date = getDateFromUIControl();
var backupDate = new Date();
backupDate.setDate(date.getDate() + 1);
However, I'm seeing a strange behaviour. Today is December 5th, 2019. If the user selects January 1, 2020 (stored in date variable), then backupDate ends up being January 2nd, 2019, instead of 2020. What is wrong with this code? How should I go about incrementing the date, if what I'm doing is wrong?
Note: because of whatever policies my company has, I can't use any JavaScript library other than jQuery.
new Date() returns the current Date(example: 05/12/2019). You are just changing the date alone in current date. Still the year is 2019.
it should be like,
date.setDate(date.getDate() + 1);
if you can't change the original date object, then it can be done like this,
var changedDate = new Date(date);
changedDate.setDate(changedDate.getDate() + 1);
var date = getDateFromUIControl();
var backupDate = new Date();
backupDate.setDate(new Date(date).getDate() + 1);
nextDay is one day after date:
var date = getDateFromUIControl();
var nextDay = new Date(date.getYear(), date.getMonth(), date.getDate()+1);
Also you don't need to worry about overflowing d.getDate()+1 (e.g. 31+1) - the Date constructor is smart enough to go into the next month.

React Native new Date() not working

I tried to get Date from datestring but it's not wokring properly.
var time = new Date('2017-12-26T02:12:00')
But when I called time.getHours() it returns 12.
I am not sure what I am doing wrong.
Use below code to get day, month and year.
var date = new Date(),
day = date.getDate(),
month = date.getMonth() + 1,
year = date.getFullYear(),
today = day+"-"+month+"-"+year;
You can change the format of date as per your requirement.
Adding below code fixed the problem
time.setMinutes(time.getMinutes() + time.getTimezoneOffset());
:)

Countdown to a single day each year (and find the date of that day in current year)

I am looking to do something quite complex and I've been using moment.js or countdown.js to try and solve this, but I think my requirements are too complex? I may be wrong. Here is the criteria...
I need to be able to have the following achievable without having to change the dates manually each year, only add it once and have many countdowns on one page.
Find current date
Find current year
Find current month
Find day within week of month that applies
¬ 3rd Sunday or 2nd Saturday
Convert to JS and output as html and run countdown
When past date - reset for following year
Pretty mental. So for example if an event is always on the 3rd Sunday of March. The date would not be the same each year.
2016 - Sunday March 19th
2017 - Sunday March 20th
2018 - Sunday March 18th etc.
I hope this is explained well, I realise it may be a total mess though. I managed to get it resetting each year with the date added manually but then someone threw in the spanner of the date being different each year.
var event = new Date();
event = new Date(event.getFullYear() + 1, 3 - 1, 19);
jQuery('#dateEvent').countdown({ until: event });
<div id="dateEvent"></div>
I have edited this answer as I have now put together a solution that works for me. As I believe this isn't simple coding due to the fact it wasn't actually answered 'Please, this is basic coding. pick up a javascript book and learn to code', yeah thanks...
// get the specific day of the week in the month in the year
function getDay(month) {
// Convert date to moment (month 0-11)
var myMonth = moment("April", "MMMM");
// Get first Sunday of the first week of the month
var getDay = myMonth.weekday(0); // sunday is 0
var nWeeks = 3; // 0 is 1st week
// Check if first Sunday is in the given month
if (getDay.month() != month) {
nWeeks++;
}
// Return 3rd Sunday of the month formatted (custom format)
return getDay.add(nWeeks, 'weeks').format("Y-MM-D h:mm:ss");
}
// print out the date as HTML and wrap in span
document.getElementById("day").innerHTML = '<span>' + getDay() + '</span>';
Using
<script src="moment.js"></script>
Hope it helps someone - I'll update when I figure how to + 1 year after it's checked current date and event has passed. I'll look in that JS book.
Please take a look at the below code, I explained in the comment what what does.
You use it by supplying a javascript Date object of any wished start date, and then add as a second value the corresponding year you wish to know the date in.
var date = new Date("2016-03-20");
function getDayInYear(startDate, year) {
// get a moment instance of the start date
var start = moment(startDate);
// collect the moment.js values for the day and month
var day = start.day();
var month = start.month();
// calculate which week in the month the date is.
var nthWeekOfMoth = Math.ceil(start.date() / 7);
// Build up the new moment with a date object, passing the requested year, month and week in it
var newMoment = moment(new Date(year,month,(nthWeekOfMoth * 7)));
// Return the next instance of the requested day from the current newMoment date value.
return newMoment.day(day);
}
var oldMoment = moment(date);
var newMoment2017 = getDayInYear(date,2017);
var newMoment2018 = getDayInYear(date,2018);
console.log(oldMoment.format('YYYY MMMM dddd DD'));
console.log(newMoment2017.format('YYYY MMMM dddd DD'));
console.log(newMoment2018.format('YYYY MMMM dddd DD'));
/** working from today up to 10 years into the future **/
var date = new Date();
var year = date.getFullYear();
for(var i = 0; i < 11; i++) {
console.log(getDayInYear(date, year+i).format('YYYY MMMM dddd DD'));
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.js"></script>

See if date selected is future from today - JavaScript

I have to compare the date that they want to put in and the current date today, and if they have put in a date that is in the future, then alert them to change the date, otherwise insert the data.
Basically I am having issues comparing the dates. here is my code:
var today = year + '-' + month + '-' + day + ' 00:00:00';
var d1 = new Date(postdate); // postdate = 2014/02/01 ie: 1 Feb 2014
var d2 = new Date(today); // todays date
if(d1>d2){
alert('You cannot post in the future!');
}
But that doesnt seem to work. Where am I going wrong?
Convert the dates into a comparable number, like milliseconds.
if(d1.valueOf()>d2.valueOf()){
alert('You cannot post in the future!');
}
You don't need to create a new variable today.
If by today you are trying to get today's date, you can simply do
var today = new Date();
var d1 = new Date(postdate); // postdate = 2014/02/01 ie: 1 Feb 2014
//----------
var d2 = new Date(year,month,day); // todays date
//----------
if(d1>d2){
alert('You cannot post in the future!');
}
Remember month is 0 based index. So, for december it would be 11.
Compare the dates with the same format, if today is 2014-01-24 00:00:00 then postdate also should be 2014-02-01 00:00:00
Then use + prefix to compare milliseconds:
if(+d1 > +d2){
alert('You cannot post in the future!');
}

Get the most recently occurring Sunday

I need to display the current week in a calendar view, starting from Sunday.
What's the safest way to determine "last sunday" in Javascript?
I was calculating it using the following code:
Date.prototype.addDays = function(n) {
return new Date(this.getTime() + (24*60*60*1000)*n);
}
var today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
var lastSunday = today.addDays(0-today.getDay());
This code makes the assumption that every day consists of twenty four hours. This is correct, EXCEPT if it's a daylight savings crossover day, in which case the day could be twenty-three or twenty-five hours.
This week, In Sydney, Australia, we set our clocks forward an hour. As a result, my code calculates lastSunday as 23:00 on Saturday.
So what IS the safest and most efficient way to determine last Sunday?
To safely add exactly one day, use:
d.setDate(d.getDate() + 1);
which is daylight saving safe. To set a date object to the last Sunday:
function setToLastSunday(d) {
return d.setDate(d.getDate() - d.getDay());
}
Or to return a new Date object for last Sunday:
function getLastSunday(d) {
var t = new Date(d);
t.setDate(t.getDate() - t.getDay());
return t;
}
Edit
The original answer had an incorrect version adding time, that does add one day but not how the OP wants.
Try this jsfiddle
It uses only built in date methods
var now = new Date();
var today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
var lastSunday = new Date(today.setDate(today.getDate()-today.getDay()));
using date-fn library: previousSunday(date)
const now = new Date(); // the date to start counting from
previousSunday(now);
Docs: https://date-fns.org/v2.25.0/docs/previousSunday

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