Calendar Timezone

Is there anyway to get the calendar component to return a date with the timestamp at midnight?

At the moment, my code looks like calendar.value[0].getTime(); and this returns something like 1559689200000.
However, pasting this into a website such as shows that it is set to midnight in my time zone, rather than UTC, meaning that the UTC time is actually 11pm the previous day.

Am I missing something obvious?
Thanks for your help