using System;

public class Program

{

    public static void Main()

    {

​

        var v = DateTime.UtcNow

               .Subtract(new DateTime(1970,1,1,0,0,0,DateTimeKind.Utc))

               .TotalMilliseconds;

​

        Console.WriteLine(v);

        v = DateTime.Now.Subtract(new DateTime(1970, 1,1)).TotalMilliseconds;

        Console.WriteLine(v);

​

        long ms = (long)DateTime.Now.ToUniversalTime().Subtract(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;

        Console.WriteLine(ms);

​

        Console.WriteLine(ToJavaScriptMilliseconds(new DateTime()));

​

    }

       static readonly long DatetimeMinTimeTicks =        (new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).Ticks;

       public static long ToJavaScriptMilliseconds(DateTime dt)

       {

          return (long)((dt.ToUniversalTime().Ticks - DatetimeMinTimeTicks) / 10000);

       }

​

​

}