Convert date to UTC using moment.js

Question

This is found in the documentation. With a library like moment, I urge you to read the entirety of the documentation. It's really important.

Assuming the input text is entered in terms of the users's local time:

 var expires = moment(date).valueOf();

If the user is instructed actually enter a UTC date/time, then:

 var expires = moment.utc(date).valueOf();

I use this method and it works. ValueOf does not work for me.

moment.utc(yourDate).format()

As of : moment.js version 2.24.0

let's say you have a local date input, this is the proper way to convert your dateTime or Time input to UTC :

var utcStart = new moment("09:00", "HH:mm").utc();

or in case you specify a date

var utcStart = new moment("2019-06-24T09:00", "YYYY-MM-DDTHH:mm").utc();

As you can see the result output will be returned in UTC :

//You can call the format() that will return your UTC date in a string 
 utcStart.format(); 
//Result : 2019-06-24T13:00:00 

But if you do this as below, it will not convert to UTC :

var myTime = new moment.utc("09:00", "HH:mm"); 

You're only setting your input to utc time, it's as if your mentioning that myTime is in UTC, ....the output will be 9:00

This will be the answer:

moment.utc(moment(localdate)).format()

localdate = '2020-01-01 12:00:00'

moment(localdate)
//Moment<2020-01-01T12:00:00+08:00>

moment.utc(moment(localdate)).format()
//2020-01-01T04:00:00Z

moment.utc(date).format(...); 

is the way to go, since

moment().utc(date).format(...);

does behave weird...

This worked for me. Others might find it useful.

let date = '2020-08-31T00:00:00Z'
moment.utc(moment(date).utc()).format() // returns 2020-08-30T22:00:00Z