Converting Year, Month, Day to momentjs Unix timestamp

user_522768 0
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I'm trying to get the same value as 1502755200000 using momentjs 

console.log(Date.UTC(2017, (8-1), 15));//1502755200000

var newDate = moment();
newDate.set('year', 2017);
newDate.set('month', 7);  // April
newDate.set('date', 15);

console.log(newDate.format('X'));//1502818350

However when I try to get the miliseconds I get 1502818350 Any idea how to get the exact same timestamp as above?

Here is the fiddle https://jsfiddle.net/cdvzoezb/1/

momentjs timestamp date javascript
2 Answers

Firstly, .format('X') gives you the unix timestamp in seconds, not milliseconds. To get milliseconds, you must use .format('x') (lowercase x).

Secondly, when you use moment(), it gives you a moment date object at your current local time, not UTC time. So when you modify it with .set('date', 15) etc, you're setting it to 15 April 2017 in your local time. This is why you're getting the vastly different value.

To get a moment date object for current UTC time, use moment.utc().

Thirdly, the Date object you created will be at time 00:00:00.000, while the moment object will be for current time. So when you set the year/month/date, time still remains at what it was when you created the object. You need to set the moment object's time to 00:00:00.000.

This can be done with the .startOf('day') function.

In conclusion:

console.log(Date.UTC(2017, (8-1), 15)); //1502755200000

var newDate = moment.utc();
newDate.set('year', 2017);
newDate.set('month', 7);
newDate.set('date', 15);
newDate.startOf('day');

console.log(newDate.format('x')); //1502755200000

Or, much shorter:

var newDate = moment.utc('2017-07-15 00:00:00.000');
user_34418820

Well you can simply create a moment object out of a Date instance and then using the utc() to convert the timestamp to UTC. After that, we can use moments method format() to get milliseconds using the x display option like so:

console.log("==============");
console.log(Date.UTC(2017, (8-1), 15));
var base = Date.UTC(2017, (8-1), 15)
var newDate = moment(base);

console.log('a', newDate.utc().format('x')); //1502755200000
user_27071950
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