Develop Reference

How to format timestamp to a calendar format date?

I'm using devExtreme dxScheduler and i'm trying to display meetings after fetching them from api, the problem is that i can't recreate the original date format ("YYYY-MM-DDThh:mm:ssZ") since i'm getting the dates as timestamp.
Here is how it's stores :
var startDate = moment("2021-05-24T16:30:00.000Z").valueOf()
// 1621873800000
Here is what i'm trying to do to recreate the format:
var startDate = moment(new Date(startDate)).format("YYYY-MM-DDThh:mm:ssZ")
//"2021-05-24T07:30:00+03:00"
Notice that the original date ("2021-05-24T16:30:00.000Z") and the formatted date ("2021-05-24T07:30:00+03:00") are different ...hence the calendar do not displays them.

Looks like the date is being converted into your local timezone, thus the difference. You may need to add Moment Timezone to be able to get the timezone back in to recreate it to the format you need. Also consider adding utc() before the format to bring it to Zulu time.

Fix 1
I see from the DevExtreme page that it needs to be displayed within this format:
currentDate: new Date(2021, 4, 27)
Maybe you need to format it before adding it like this:
var check = moment("2021-05-24T16:30:00.000Z", 'YYYY/MM/DD');
var month = check.format('M');
var day = check.format('D');
var year = check.format('YYYY');
console.log(month,day,year);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
And then in your dxScheduler add the property like this:
currentDate: new Date(year, month, day);
Fix 2
If that's not the problem, you can install moment-timezone
var a = moment.utc("2013-11-18 11:55").tz("Asia/Taipei");
var b = moment.utc("2013-11-18 11:55").tz("America/Toronto");
a.format(); // 2013-11-18T19:55:00+08:00
b.format(); // 2013-11-18T06:55:00-05:00
a.utc().format(); // 2013-11-18T11:55Z
b.utc().format(); // 2013-11-18T11:55Z
In this example, you first create moment.utc("2013-11-18 11:55") object in UTC, and then change its timezone to specified. This also works if you create the object in your default timezone: moment("2013-11-18 11:55").
Note that created moments have equal UTC time because these moments were created in a default timezone.

Turns out that displaying a calendar event with DevExtreme requires only to use regular date object.... so no need to do anything spacial.

How to get previous month and expected format from month picker using moment JS

I am using jquery.ui.monthpicker library. For month picker I am getting date like 07/2017. From this date string I need to calculate previous month and formatted like 1707 using moment js library.
any help would be appreciated.

This code may solve your problem.
moment("07/2017", "MM/YYYY").subtract(1, 'months').format('YYMM');

DEMO at https://jsfiddle.net/nffswx75/
var dt = "07/2017";
alert(moment(dt,"MM/YYYYY").format('YYMM'));
alert(moment(dt,"MM/YYYYY").add(-1, 'months').format('YYMM'));
alert(moment(dt,"MM/YYYYY").subtract(1, 'months').format('YYMM'));

You can let moment create a date object from a string by telling it what format your date is in.
let dateString: string = "07/2017";
var date = moment(dateString, "MM/YYYY").subtract(1, 'month').format("YYMM");

JavaScript date displaying the wrong day and time

I have this application where I want to use you date, but the problem is that the date is not working as I expect.
I create a date object like this:
// Get today's date
today: function () {
// Create a new date
var date = new Date();
// Set to midnight
date.setHours(0, 0, 0, 0);
// Return our date
return date;
},
and If I output that date in my view I get yesterdays date at 23:00 hours....
Which looks like this:
2015-07-08T23:00:00.000Z
Does anyone know how I can get the date to be formatted properly?
Update
Just to elaborate a bit, I want to use the date to compare against records in the database. These records have the date applied to them, because the JavaScript is showing the local date time, it is not comparing correctly. Also there is a case where I am saving that date and I don't want it to save the local date.

based on your culture setting you can use the
date.toLocaleDateString()
this will give localized string format back

date.toUTCString();
date.toLocaleString();
date.toLocaleDateString();
date.toDateString();
date.toISOString();
Find your answer here :) And the best option is to use momentjs http://momentjs.com/

So, I ended up creating this function:
// Converts a date to a timeStamp
this.convertToTimeStamp = function (dateTime) {
// Get just the date
var date = dateTime.toDateString();
// Get the timestamp
var timeStamp = Date.parse(date);
// Return our timeStamp
return timeStamp;
};
If my understanding is correct, that should create the same date no matter what timezone / locale you are in.

How to get date format in Angular-JS

My requirement is something different. I want to get the date format, not to format the date. Means I have a date string and now I want to get the date format of that date and apply it to the another date as a format.
Let me explain in brief with example:
var dateStr = "2015-06-06T12:00:00Z";
var d = new Date(dateStr);
here my date format is yyyy-MM-ddTHH:mm:ssZ you can see in dateStr object.
Now i will create another date and want to apply the same date-format to this new date.
var formatStr = "yyyy-MM-dd'T'HH:mm:ss'Z'"; // want to get this from above date, not hard coded like this.
var newDate = $filter('date')(d, formatStr);
here you can see that i have hard coded the format string, which i don't want to do. Here this string should be come from the above d date/or dateStr String.

You can do it by using momment.js
http://momentjs.com/downloads/moment.js
van date=new Date(date);
var dateInFormate=moment(date);
var date=dateInFormate.format('yyyy-MM-ddTHH:mm:ssZ');

As #Rob said, there is doubt on the reliably for all formats. What you need is pre defined map with key being the format and value being its corresponding regular expression.
Now, create a function with input as dateStr and will return the format. Like
function getDateFormat(dateStr) {
var format = default_format;
// Check in map for format
// If you get the format in map, return that else return a default format.
return format;
}

Date from string in format javascript google apps script

In my web app user needs to fill the fields like date and time.
In date they can enter a date in a format:
d/m/yy
or
dd/mm/yy
(unfortunately I can't control how exactly user will enter it)
And they can also pick a time from the drop-down list:
08:00am,8.30am, 09:00am,.... , 05:00 pm
Now, I am trying to convert time and date strings it into a valid date object using function below, but I am getting "Date isInvalid Date" output.
How should I proceed with it?
var timeStartString ="1970/01/01 "+ "10:00am";
var st1 =createDate("1/12/2013",timeStartString);
Logger.log("Date is"+st1);
function createDate(dateString,timeString)
{
var eventDate = new Date(dateString);
var eventTime = new Date(timeString)
message +="Date String:"+dateString + " timeString "+timeString;
eventTime.setFullYear(eventDate.getFullYear());
eventTime.setDate(eventDate.getDate());
eventTime.setMonth(eventDate.getMonth());
return eventTime;
}

You may want to look into using the Moment.js library, which makes date parsing and manipulation in JavaScript a bit easier. More information on how to use it in Apps Script here. If the date format is consistent, then you can use a custom format string to parse it.
var date = moment('1970/01/01 10:00am', 'YYYY/MM/DD HH:mma').toDate();

The Date class won't recognize the time if am or pm is directly attatched to the time. For example new Date("1/12/2013 10:00am") will return Invalid Date, whereas new Date("1/12/2013 10:00 am") will return Sat Jan 12 2013 22:00:00. It's a subtle difference, but that's the way the parser is built. You shouldn't need the createDate method at all if you concatenate the date with the properly formatted time string.