Passing javascript Date object to C# WebBrowser control using window.external

Question

I am able to call C# methods of WebBrowser.ObjectForScripting with javascript window.external from WebBrowser WinForms control and pass string, int, bool etc. However I don't know how to pass javascript Date object and somehow convert/marshal it to .NET DateTime class.

Obviously, I could pass a string and parse it, but this is really not the point. I'm just curious how could I do it with javascript Date and .NET DateTime?

Frédéric Hamidi · Answer 1 · 2011-04-18T09:08:01.620

3

You can take advantage of the fact that dates in Javascript are expressed as the number of milliseconds elapsed since the UNIX epoch (1970-01-01 00:00:00 UTC). Use the valueOf() method to obtain that value from a Date object :

var millisecondsSinceEpoch = yourDate.valueOf();

If you can marshal that value to C# as a double, you can create the appropriate DateTime object using its constructor and the AddMilliseconds() method:

DateTime yourDateTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)
    .AddMilliseconds(millisecondsSinceEpoch);

edited Apr 18 '11 at 09:08

answered Apr 18 '11 at 08:56

Frédéric Hamidi

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I could do that, but I am looking only for solution for how to read javascript `Date` object in C#. I'm not even sure if that's possible, but if it's not, that's ok. But I'm hoping that there is some way to do that. – prostynick Apr 18 '11 at 09:36
There are no "Javascript Date objects" in C# – Magnus Apr 18 '11 at 09:48
As far as I understand, when I pass `Date` object to C# it's marshaled using COM, so I suppose it's possible to do it. – prostynick Apr 18 '11 at 11:19

score 1 · Accepted Answer · answered Apr 18 '11 at 13:53

I finally got it working. I don't know why, but I am unable to use it with dynamic. Here is the solution:

[ComVisible(true)]
public class Foo
{
    public void Bar(object o)
    {
        var dateTime = (DateTime)o.GetType().InvokeMember("getVarDate", BindingFlags.InvokeMethod, null, o, null);
        Console.WriteLine(dateTime);
    }
}

score 1 · Answer 3 · edited Jul 10 '11 at 02:15

1

I found better solution for my project.

in javascript:

var date = new Date();
myComObject.DoSomething(date.getVarDate());

in C#

[ComVisible(true)]
public class Foo
{
    public void Bar(DateTime dateTime)
    {
        Console.WriteLine(dateTime);
    }
}

edited Jul 10 '11 at 02:15

slugster

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answered May 25 '11 at 08:02

Mentor

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Of course it's possible, but I was wondering how to do that without calling `getVarDate` in javascript. – prostynick May 25 '11 at 09:45

Passing javascript Date object to C# WebBrowser control using window.external

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