Explanation for Timespan Differences Between C# and JavaScript

Question

This is based on Computing milliseconds since 1970 in C# yields different date than JavaScript and C# version of Javascript Date.getTime().

For all of these calculation

Answer 1

I understand that JavaScript Date objects are based on the Unix Epoch (Midnight on Jan 1, 1970).

Yes, they are. Internally, it's just a number of milliseconds from the epoch. But when you call the date constructor, or look at the output from .toString(), it is using the local time of where the code is running.

If you want the input to be specified in UTC, then you have to use a different incantation:

var ts = Date.UTC(2014,1,28);  // returns a numeric timestamp, not a Date object

var dt = new Date(ts);         // if you want a date object

var s = dt.toUTCString();      // if you want the output to be in UTC