Develop Reference

To convert date format to the time stamp

How to calculate the start of the day.
I calculate by
=> moment().startOf('day').toISOString()
it returns
2019-09-12T00:00:00.000
But I want to in this format "2019-09-12 00:00:00.000"
How can we get,Please help me.

var formatedDate= moment().startOf('day').format('YYYY-MM-DD HH:mm:ss,sss');

Instead of using .toISOString() method you can simply use format().
As per momentjs doc here
.toISOString() returns a timestamp in UTC, even if the moment in
question is in local mode.
Use it like this:
moment().startOf('day').format('YYYY-MM-DD hh:mm:ss:SSS')
Hope this helps happy coding!!!

Foreign Time to Local Time

I'm trying to convert foreign time to Local Time. I'm getting a date and time in Europe/London. Currently I'm using moment-timezone to get my code working, however its giving me a wrong output.
resultDate = new moment('2017-06-30T22:10:00').tz('Europe/London').format('YYYY-MM-DD HH:mm:ss');
I think the code thinks that the date input is already in local time where I need to convert it into Europe/London which would give a local result, where as what I want is to actually convert the foreign time to local time.
In short the date and time as my input (2017-06-30T22:00:00), I am expecting it to be 7 hours in advance (2017-07-1T05:00:00) since I currently live in Asia/Manila, 7 hours in advance to London. However I'm getting 2017/06/30 15:00:00 +0100 as my result.
Is there a way for me to do this by utilizing the information 'Europe/London' or 'Asia/Manila' as seen in my code?

You can use moment.tz to parse your input as Europe/London time and then use the tz function to convert it to Asia/Manila.
The first parses your input using the given timezone while the latter convert a moment objet to a given timezone.
Here a working sample:
// Parse input considering as London tz
var timeInLondon = moment.tz('2017-06-30T22:10:00', 'Europe/London');
// Converting input to Manila
var timeInManila = timeInLondon.tz('Asia/Manila');
// Show result
console.log(timeInManila.format('YYYY-MM-DD HH:mm:ss'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment-timezone/0.5.11/moment-timezone-with-data-2010-2020.min.js"></script>

option to display the time in PST by converting milliseconds

i am working on javascript. and i have time in milliseconds. so i have to display the time in PST time Zone. i have tried for GMT. but is there any option to display the time in PST format in which the input is in milliseconds like 1671673550214. so iam trying to convert this milliseconds to time and date format of PST. same as the below code does. pleas help.
Here is my tried code:
var time = new Date().getTime();
var date = new Date(time);
document.write(date.toString());
i have even tried of using UTCString(), UTC() and toString(); but things is getting converted to GMT and not to PST.

Please check this library, it has lot of functions to display and manupilate date time.
http://momentjs.com/
http://momentjs.com/docs/
Also please check following post
Moment.js: Format date in a specific timezone\
If you dont want to use external lib, see the following article
http://www.techrepublic.com/article/convert-the-local-time-to-another-time-zone-with-this-javascript/6016329

You can use timezonjs which help you to convert the time to any timezone.
https://github.com/mde/timezone-js

Convert from string with milliseconds to date object Javascript

I got this problem when dealing with date time conversion. I have timestamp data from postgreSQL database with format like this one
"2011-04-04 19:27:39.92034"
In order to display it in highcharts, I have to convert it to date or time object. Without milliseconds, I easily convert it with Date.js
But milliseconds can't be handled with that library. I tried also with Date.parse but always got NaN.
Any solution for this problem? Thank you

JS built in Date class should be able to handle this, and getTime() can return milliseconds since start 1970 (UNIX time). Watch out for time zone issues though; the constructor may interpret the date/time as being local, but getTime()'s milliseconds since 1970 may be in UTC, baking in a conversion that is difficult to remove.
new Date("2011-04-04 19:27:39.92034").getTime()
1301941659920

Many ways to Rome. The given code will return '(datestr=) 2011-4-4 19:27:39.92'. Is that what you look for?
var darr = '2011-04-04 19:27:39.92034'.split('.')
, dat=new Date(darr[0])
, datestr = '';
dat.setMilliseconds(Math.round(darr[1]/1000));
datestr = [ [dat.getFullYear(),dat.getMonth()+1,dat.getDate()].join('-')
,' ',
[dat.getHours(),dat.getMinutes(),dat.getSeconds()].join(':')
,'.',
dat.getMilliseconds()
].join('');

Can't you just cut of the last 6 chars of that string? You might then round the miliseconds and eventually add a second to you time object.

This is simpler and in one line:
new Date('01/09/2015 06:16:14.123'.split(".")[0])

How to get difference of saved time and current time in jquery?

I want to get the time difference between saved time and current time in javascript or jquery. My saved time looks like Sun Oct 24 15:55:56 GMT+05:30 2010.
The date format code in java looks like
String newDate = "2010/10/24 15:55:56";
DateFormat format = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = format.parse(newDate);
How to compare it with the current time and get the difference?
Is there any inbuilt function in jquery or javascript??
Any suggestions or links would be appreciative!!!
Thanks in Advance!
Update
Date is stored as varchar in the DB. I am retriving it to a String variable and then change it to java.util.Date object. The java code looks like
String newDate = "2010/10/24 15:55:56";
DateFormat format = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = format.parse(newDate);
This date object was sent to client. There i want to compare the saved date with current date and want to show the time difference like 2 secs ago, 2 hours ago, 2 days ago etc... like exactly in facebook. I have gone through some date to timestamp conversion tutorial in java script and now i can get the difference in timestamp. Now, i want to know how i shall change it to some format like "2 secs or 2 days or 24 hours"??. Or, how i shall change it back to date format???

Convert them into timestamps which are actually integers and can get subtracted from each other. The you just have to convert back the resulting timestamp to a javascript date object.
var diff = new Date();
diff.setTime( time2.getTime()-time1.getTime() );

You dont need to explicit convert, just do this:
var timediff = new Date() - savedTime;
This will return the difference in milliseconds.

jQuery doesn't add anything for working with dates. I'd recommend using Datejs in the event that the standard JavaScript Date API isn't sufficient.
Perhaps you could clarify exactly what input and output you're aiming for. What do you mean by "the difference?" There is more than one way to express the difference between to instants in time (primarily units and output string formatting).
Edit: since you said you're working with jQuery, how about using CuteTime? (Demo page)