passing a C# object to Javascript never get the assigned value

Question

In c# code behind i am creating an object and try to access that in front-end javascript. but it is always getting instantiate value but not the object value; Please see the code below:

public class Product
{
    public String[] Sizes { get; set; }
    public decimal Price { get; set; }
    public DateTime Expiry { get; set; }
    public string Name { get; set; }
}

public partial class _Default : System.Web.UI.Page
{
    public string sJSON = "shuvra";

    public JavaScriptSerializer javaSerial = new JavaScriptSerializer();

    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void Btn2_Click(object sender, EventArgs e)
    {
        System.Text.StringBuilder sb = new System.Text.StringBuilder();

        Product product = new Product
        {
            Name = "Apple",
            Expiry = new DateTime(2008, 12, 28),
            Price = 3.99M,
            Sizes = new[] { "Small", "Medium", "Large" }
        };

        var oSerializer = new System.Web.Script.Serialization.JavaScriptSerializer();

        sJSON = oSerializer.Serialize(product);

        JavaScriptSerializer ser = new JavaScriptSerializer();

        //ser.Serialize(arrayMarker, jasonSerialize); 

        sb.AppendLine("markicons();");

        ScriptManager.RegisterStartupScript(up_IFASelected, typeof(UpdatePanel), this.ClientID + "_LoadMap", sb.ToString(), true);
    }
}

The javascript code:

 function markicons() {
        initialize();

        var a = JSON.parse('<%= this.javaSerial.Serialize(this.arrayMarker) %>');

        var b = eval('<%=this.sJSON%>');
}

The value 'b' is always shuvra but not the assigned value. How can i fix it?