How to return a JavaScript 'native' array from a C# method?

Question

I'm trying to call a C# method from JavaScript by using ActiveXObject:

var myobj = new ActiveXObject('myobject');
var arr = myobj.GetArray();

Eventually, arr will contain a SAFEARRAY object, but not JScript array. Is there any way to return native JavaScript object from a C# method?

Answer 1

You can return a JSON string and then parse into a JavaScript object. There are a number of .NET libraries available to serialize .NET objects into JSON and vice-versa-

• JSON.NET
• Microsoft ASP.NET AJAX library
• JSONSharp

to name a few.

This question and answer may be of use to you

Answer 2

I found the solution by myself, but no documentation exists for this part. The solution is to use JScript.ArrayObject in the following way:

ArrayObject _lastField;
byte[] byteArray = new byte[]{2,1,2,3};
object[] array = new object[byteArray.Length];
byteArray.CopyTo(array, 0);
_lastField = Microsoft.JScript.GlobalObject.Array.ConstructArray(array);

After that you will be able to use the _lastField array in JavaScript like a native array:

var myobj = new ActiveXObject('myobject');
var arr = myobj.LastField;
alert(arr[1]);

Answer 3

You may return delimited Joined String in C# and can split into JavaScript

//C#
public string getArryString()
{
string[] arrstring = new string[]{"1","2","3"};
return string.Join(",", arrstring);
}

//Javascript
var arrstring = objActiveX.getArryString().split(',');

Answer 4

Via VBArray it can work like this:

1. Return object[] from C# (declare so in the dispinterface).

2. To get a native JS array in JScript use VBArray:

   var jsArray = new VBArray(myobj.GetArray()).toArray();
   for (i = 0; i < jsArray.length; i++) 
   {
      // use jsArray[i]
   }
   

Background information:

• JScript supports SafeArrays of Variants only http://blogs.msdn.com/b/jaiprakash/archive/2007/01/09/jscript-supports-safearrays-of-variants-only.aspx

• Eric's Complete Guide To Type Signatures Of Scriptable Object Models http://blogs.msdn.com/b/ericlippert/archive/2004/07/14/183241.aspx