Why moment js gives different milliseconds?

Question

I getting error of different millisecond of same date using moment js.

I am getting data from server ('-2208988800000'). I converted the value in 'DD-MMM-YYYY'. Now I want again same millisecond, why I am getting different milliseconds of same date? Here is my code

http://plnkr.co/edit/1QoWLoFqkNAe2ebZ0V01?p=preview

I have two console x1 and x2. They are different, why?

var x = '-2208988800000'
var d = new Date(moment(new Date(parseInt(x)).toUTCString()).format('DD-MMM-YYYY'));
console.log(d)
var x2 = moment(new Date(d).toUTCString()).format('x');
console.log(x2)
// why x1 and x2 is different

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.22.2/moment.min.js"></script>

How can I get the same value?

Answer 1

When you format the date to DD-MMM-YYYY you're losing hours and minutes, that's part of the reason

Try updating your code to

var d = new Date(moment(new Date(parseInt(x)).toUTCString()).format('DD-MMM-YYYY HH:mm:ss'));

and you will get a timestamp that is closer

Answer 2

You've got a terrible amount of manipulation back and forth between moment objects, date objects, and strings. It's unclear what you actually want to accomplish, but none of that should be necessary.

As to the result, the first call to the date constructor is getting the string value '31-Dec-1899', and thus you can reduce the example to:

var d = new Date('31-Dec-1899');
console.log(+d);

This will give different results depending on what browser you're running (because the implementation of parsing by the date object is implementation dependent when not in a standard format), and it will vary by time zone where the code is run (because it's assumed the value is in terms of local time).

For me, running in Chrome 70 on Windows 10, in the US Pacific time zone, this logs -2209046400000. You may get different results.

In general, don't do so much manipulation. Most functions you could want are built in to Moment. Any time you find yourself converting to strings and back to objects, or using the Date constructor, you're probably introducing bugs.