Adding Data Using Silverlight and Javascript Client Object Model

Silverlight

private void Add_Click(object sender, RoutedEventArgs e)
{
    ClientContext ctx = new ClientContext("Your Server Here");
    List announcements = ctx.Web.Lists.GetByTitle("Announcements");

    ListItemCreationInformation createInfo = new ListItemCreationInformation();
    ListItem newItem = announcements.AddItem(createInfo);
    newItem["Title"] = "A new item";
    newItem.Update();
    ctx.ExecuteQueryAsync((s, args) =>
    {
        Dispatcher.BeginInvoke(() =>
        {
            label1.Content = "Item Added";
        });
    }, (s, args) =>
    {
        Dispatcher.BeginInvoke(() =>
        {
            label1.Content = args.Message;
        });
    });
}

Javascript

function Add_Click() {
    var ctx = new SP.ClientContext.get_current();
    var announcements = ctx.get_web().get_lists().getByTitle("Announcements");

    var createInfo = new SP.ListItemCreationInformation();
    var newItem = announcements.addItem(createInfo);
    newItem.set_item("Title", "A new javascript item");
    newItem.update();

    ctx.executeQueryAsync(function (s, args) {
        var console = document.getElementById("DemoConsole");
        console.innerHTML = "Add Completed";
    }, null);
}

For more information on Silverlight and JavaScript Client Object Model, see below:

• How To Referencing the JavaScript Client Object Model
• Retrieving Data Using Silverlight and JavaScript Client Object Model
• Updating Data Using Silverlight and Javascript Client Object Model
• Deleting Data Using Silverlight and Javascript Client Object Model