What is equivalent of DateTime.ToOADate() in javascript?

Question

How can I get the OADate (OLE Automation date) in javascript? I need to pass my date object (to my web service) in the form of a double value.

in c#:

Answer 1

with time zone offset repair:

function toOADate(date) {
    var msPerDay = 24 * 60 * 60 * 1000;
    var baseDate = new Date("1899-12-30T00:00:00.000+0000");
    return (date.getTime() - baseDate.getTime() - 60*1000*getTimezoneOffset()) / msPerDay;
}