Loading and Passing JScript Arrays from/to C# (not C) COM Component

Question

I have looked at tutorials on jscript arrays, but not seeing it yet. I saw something similar asked but involving Win32 code not .NET.

Wondering, how do I pass arrays bac

Answer 1

Microsoft JScript engine implements JavaScript arrays as IDispatchEx objects. From C#, they can be manipulated via reflection or as dynamic objects (with dynamic, it's only possible to access properties and methods like length, push() etc., but not reference actual elements by their indices). Example:

JavaScript:

var T = new ActiveXObject("MySimulator.World"); 

var ar = ["a", "b", "c"];

T.MyFunction(ar);

C#:

public void MyFunction(object array)
{
    dynamic dynArray = array;
    int length = dynArray.length;
    dynArray.push("d");

    SetAt(array, 1, "bb"); 

    Console.WriteLine("MyFunction called, array.length: " + length);
    Console.WriteLine("array[0]: " + GetAt(array, 0));
    Console.WriteLine("array[1]: " + GetAt(array, 1));
    Console.WriteLine("array[3]: " + GetAt(array, 3));
}

static object GetAt(object array, int index)
{
    return array.GetType().InvokeMember(index.ToString(),
        System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.GetProperty,
        null, array, new object[] { });
}

static object SetAt(object array, int index, object value)
{
    return array.GetType().InvokeMember(index.ToString(),
        System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.SetProperty,
        null, array, new object[] { value });
}

Output:

MyFunction called, array.length: 3
array[0]: a
array[1]: bb
array[3]: d