DateTime to javascript date

Question

From another answer on Stackoverflow is a conversion from Javascript date to .net DateTime:

long msSinceEpoch = 1260402952906; // Value from Date.getTime() in JavaScript return new DateTime(1970, 1, 1) + new TimeSpan(msSinceEpoch * 10000); 

But how to do the reverse? DateTime to Javascript Date?

Answer 1

Try:

return DateTime.Now.Subtract(new DateTime(1970, 1,1)).TotalMilliseconds 

Edit: true UTC is better, but then we need to be consistent

return DateTime.UtcNow                .Subtract(new DateTime(1970,1,1,0,0,0,DateTimeKind.Utc))                .TotalMilliseconds; 

Although, on second thoughts it does not matter, as long as both dates are in the same time zone.

Answer 2

JavaScript Date constructor accepts number of milliseconds since Unix epoch (1 January 1970 00:00:00 UTC). Here’s C# extension method that converts .Net DateTime object to JavaScript date:

public static class DateTimeJavaScript {    private static readonly long DatetimeMinTimeTicks =       (new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).Ticks;     public static long ToJavaScriptMilliseconds(this DateTime dt)    {       return (long)((dt.ToUniversalTime().Ticks - DatetimeMinTimeTicks) / 10000);    } } 

JavaScript Usage:

var dt = new Date(<%= DateTime.Today.ToJavaScriptMilliseconds() %>); alert(dt);