Using Ajax.BeginForm with ASP.NET MVC 3 Razor

Example:

Model:

public class MyViewModel
{
    [Required]
    public string Foo { get; set; }
}

Controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View(new MyViewModel());
    }

    [HttpPost]
    public ActionResult Index(MyViewModel model)
    {
        return Content("Thanks", "text/html");
    }
}

View:

@model AppName.Models.MyViewModel

<script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>

<div id="result"></div>

@using (Ajax.BeginForm(new AjaxOptions { UpdateTargetId = "result" }))
{
    @Html.EditorFor(x => x.Foo)
    @Html.ValidationMessageFor(x => x.Foo)
    <input type="submit" value="OK" />
}

---

and here's a better (in my perspective) example:

View:

@model AppName.Models.MyViewModel

<script src="@Url.Content("~/Scripts/jquery.validate.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/index.js")" type="text/javascript"></script>

<div id="result"></div>

@using (Html.BeginForm())
{
    @Html.EditorFor(x => x.Foo)
    @Html.ValidationMessageFor(x => x.Foo)
    <input type="submit" value="OK" />
}

index.js:

$(function () {
    $('form').submit(function () {
        if ($(this).valid()) {
            $.ajax({
                url: this.action,
                type: this.method,
                data: $(this).serialize(),
                success: function (result) {
                    $('#result').html(result);
                }
            });
        }
        return false;
    });
});

which can be further enhanced with the jQuery form plugin.

I think that all the answers missed a crucial point:

If you use the Ajax form so that it needs to update itself (and NOT another div outside of the form) then you need to put the containing div OUTSIDE of the form. For example:

 <div id="target">
 @using (Ajax.BeginForm("MyAction", "MyController",
            new AjaxOptions
            {
                HttpMethod = "POST",
                InsertionMode = InsertionMode.Replace,
                UpdateTargetId = "target"
            }))
 {
      <!-- whatever -->
 }
 </div>

Otherwise you will end like @David where the result is displayed in a new page.

I got Darin's solution working eventually but made a few mistakes first which resulted in a problem similar to David (in the comments below Darin's solution) where the result was posting to a new page.

Because I had to do something with the form after the method returned, I stored it for later use:

var form = $(this);

However, this variable did not have the "action" or "method" properties which are used in the ajax call.

$(document).on("submit", "form", function (event) {
    var form = $(this);

    if (form.valid()) {
        $.ajax({
            url: form.action, // Not available to 'form' variable
            type: form.method,  // Not available to 'form' variable
            data: form.serialize(),
            success: function (html) {
                // Do something with the returned html.
            }
        });
    }

    event.preventDefault();
});

Instead you need to use the "this" variable:

$.ajax({
    url: this.action, 
    type: this.method,
    data: $(this).serialize(),
    success: function (html) {
        // Do something with the returned html.
    }
});