You can use following in your Global.asax.cs file:
protected void Application_BeginRequest(object sender, EventArgs e)
{
if (HttpContext.Current.Request.HttpMethod == "OPTIONS")
{
HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE");
HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "Content-Type, Accept");
HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000");
HttpContext.Current.Response.End();
}
}