Develop Reference

Javascript : Increase a Date object by a year

I'm assign a new date object to my object attribute like that :
giftObject.purshasedDate = new Date()
which give a date format :
Date Thu Feb 20 2020 13:36:37 GMT+0100 (heure normale d’Europe
centrale)
I want to increase this date by one year, I tried :
new Date().setFullYear(giftObject.purshasedDate.getFullYear() + 1) but it give a number serial like this : 1613824899244
I do not understand what that number serial mean! it's a date or should a try some thing else ?

By default all dates object are timestamps.
JavaScript Date objects represent a single moment in time in a
platform-independent format. Date objects contain a Number that
represents milliseconds since 1 January 1970 UTC.
Source : https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
I think the default new Date() object can display itself to string by in fact it's also a timestamp.
If you want to display a date as string, you have to use the toLocaleString() method on Date.
I tried by updating the original date and it return the string of the date, don't know why but it's work by updating the original date.
Example :
let giftObject = {};
giftObject.purshasedDate = new Date();
giftObject.purshasedDate.setFullYear(giftObject.purshasedDate.getFullYear() + 1);
console.log(giftObject.purshasedDate)
Result : "20/02/2021 à 13:55:49" for my French browser

const oldDate = new Date("Date Thu Feb 20 2020 13:36:37 GMT+0100")
const newDate = oldDate.setFullYear(oldDate.getFullYear() + 1)
const dateWithPlusOneYear = new Date(newDate)
console.log(new Date(dateWithPlusOneYear))
//Sat Feb 20 2021 13:36:37 GMT+0100 (Central European Standard Time)

Please use this one:
purshasedDate = new Date();
purshasedDate = new Date(purshasedDate.setFullYear(purshasedDate.getFullYear() + 1));

datetime convert to date string - javascript

I have following datetime value in a json :
Fri Jan 22 2016 14:34:38 GMT-0500
I would like to display something like "January 22, 2016"
How could I achieve this in javascript. I have JQuery, Extjs libraries available.

Try creating object having properties of abbreviated months, values of full month, using for..in loop , String.prototype.slice(), String.prototype.replace()
var months = {
"Jan":"January",
"Feb":"February",
"Mar":"March",
"Apr":"April",
"May":"May",
"Jun":"June",
"Jul":"July",
"Aug":"August",
"Sep":"September",
"Oct":"October",
"Nov":"November",
"Dec":"December"
};
var date = "Fri Jan 22 2016 14:34:38 GMT-0500";
// extract "Jan 22 2016" from `date`
var d = date.slice(4, -18);
for (var prop in months) {
if (new RegExp(prop).test(d)) {
// replace abbreviated month with full month name
d = d.replace(prop, months[prop]);
// replace day with day followed by comma `,` character
d = d.replace(/(\d{2})(?=\s)/, "$1,")
}
}
document.body.textContent = d

This question is addressed to the same question of yours. You can use the functions shown here to construct the date string as you want.
// This could be any Date String
var str = "Fri Feb 08 2013 09:47:57 GMT +0530 (IST)";
var date = new Date(str);
This will then give you access to all the Date functions (MDN)
For example:
var day = date.getDate(); //Date of the month: 2 in our example
var month = date.getMonth(); //Month of the Year: 0-based index, so 1 in our example
var year = date.getFullYear() //Year: 2013
Extract date and time from string using Javascript

Found this crazy method here, but worked!
Converting milliseconds to a date (jQuery/JS)
Here is the fiddle that i'v done
https://jsfiddle.net/Ripper1992/hj6L2Lvz/
var now = new Date("Fri Jan 22 2016 14:34:38 GMT-0500");
alert(now.customFormat( "#MMMM# #DD#, #YYYY#" ) );
customFormat is the function called to get each part of the Data, parse and replace based on the #MMMM# or #DD# or #SS# defined by the user.
And here is the complete function with the documentation
http://phrogz.net/JS/FormatDateTime_JS.txt

convert a date time string into a DateTime object to update in Sharepoint list DateTime field

I am just trying to update my Share Point list column of type Date Time.
I have a string in which I have a date in below format
Friday, January 09, 2015 1PM
now I want to convert this string into a Date Time object so that I can be able to update my Share Point List column which is of type Date Time in below format,
1/9/2015 1:00 PM
FYI I am using JSOM, so all my code is written in JavaScript.

You can send as it is and parse it in dot net sharepoint.
string date = "Friday, January 09, 2015 1PM";
DateTime time = DateTime.Parse(date);
or any format like
DateTime.Parse("Friday, January 09, 2015 1PM", new CultureInfo("en-US"));
or if you want in JS it will be
var current= "Friday, January 09, 2015 1PM";
var splitDate = current.split(",");
var splitMonthName = splitDate[1].trim().split(" ");
var month = getMonthFromString(splitMonthName[0]);
var day = splitMonthName[1];
var year = splitDate[2].trim().split(" ");
var myDate = month+"/"+ day+"/"+year[0];
function getMonthFromString(mon)
{
return new Date(Date.parse(mon +" 1, 2012")).getMonth()+1
}

Add Number of months to a Date in a text field

function addDays(){
var myDate =document.getElementById('treatdate');
var numberOfDaysToAdd = document.getElementById('resultdays');
var tset = numberOfDaysToAdd.value;
var result1 = myDate.value.addMonths(parseInt(tset));
var pldate= moment(result1).format('YYYY-MM-DD');
return pldate; }
'treatdate' is an id for a treatment date which is pulled from my database. Thanks in advance.

You can always use moment.js library for Date manipulations. http://momentjs.com/
For your problem you can do the following.
function addDays(){
var datefrmDb = $('#treatdate').val();
var monthstoadd= $('#resultdays').val();
var new_date = (moment(datefrmDb, "YYYY-MM-DD").add('months', monthstoadd)).format("YYYY-MM-DD");
return new_date;
}

If your date format is yyyy-MM-dd
var myDate = new Date(document.getElementById('treatdate').value);
this will a date and time.
Example:
var dd = new Date("2014-02-02 11:11:11")
console log
Sun Feb 02 2014 11:11:11 GMT+0000 (GMT Standard Time)

See if this snippet can help you understand how to manipulate dates. To change/add the months to a Date() object you can use the setMonth() method.
numberOfMonthsToAdd = 5; // the number of months that you want to add
date = new Date(); // creating a Date object
date.setMonth(numberOfMonthsToAdd); // adding the number of months
Note that you may add numbers beyond 12 - the object handles the date, and jumps to the next year.

Unexpected Date result from using Number and Split

Why does the following code:
newDate = "2-24-2014";
var splitDate = newDate.split('-');
var dateObj = new Date(Number(splitDate[0]), Number(splitDate[1]) - 1, Number(splitDate[2]));
Produce the following?:
Sat Jun 05 1909 00:00:00 GMT+0100 (GMT Daylight Time)
I know the formatting but not the strange date itself. I was wondering if it had something to do with Number but cant seem to find any answers on this.

new Date(Year, Month, Date)
The above is the actual format. Whereas you have given like new Date(Month, Date, Year)
var dateObj = new Date(Number(splitDate[2]), Number(splitDate[0]) - 1, Number(splitDate[1]));

the problem is the order of parameters:
new Date(Number(splitDate[2]), Number(splitDate[0]) - 1, Number(splitDate[1]));
or simply do this:
new Date(Date.parse("2-24-2014"))