index.cshtml

<form action="/api/values" method="post">
    <input type="text" name="value"  />
    <input type="submit" value="Submit" />
</form>

<form id="fooForm" action="/api/values" method="post">
    <input type="text" name="value"  />
    <input type="submit" value="Submit" />
</form>


@section scripts{
    <script type="text/javascript">
        $(function () {
            $("#fooForm").submit(function (e) {

                $.ajax({
                    url: this.action,
                    type: "POST",
                    //None of the options below works
                    //data: JSON.stringify({ value: $(this).find("input[name=value]").val() })
                    data: ({ value: $(this).find("input[name=value]").val() })
                });

                e.preventDefault();
            });
        });
    </script>
}

raw_request.txt

without JSON.stringify
--------------------------------------

POST http://localhost:2547/api/values HTTP/1.1
Host: localhost:2547
Connection: keep-alive
Content-Length: 9
Origin: http://localhost:2547
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.75 Safari/535.7
Content-Type: application/x-www-form-urlencoded
Accept: */*
Referer: http://localhost:2547/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Cookie: .ASPXAUTH=502750FAA18C2116E8F6F952CF16DE324DDA73B64758CD7B28B7026E65377F3EFFB6722B004805E60F2324B061BA2298DF31E32D230D9F189C693E060DA0B83DC1FF894B5589065AA7630758DC513732096E0D9DDFA051E467E029A91B9DD6A793212585573D88280DAB9BA0CB73A43732B2D8E6C7D896D56E0E92F60B209968E076A78E14965BC9C38B22B07D49DD75

value=fff

with JSON.stringify
-------------------------------------
POST http://localhost:2547/api/values HTTP/1.1
Host: localhost:2547
Connection: keep-alive
Content-Length: 15
Origin: http://localhost:2547
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.75 Safari/535.7
Content-Type: application/x-www-form-urlencoded
Accept: */*
Referer: http://localhost:2547/
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Cookie: .ASPXAUTH=502750FAA18C2116E8F6F952CF16DE324DDA73B64758CD7B28B7026E65377F3EFFB6722B004805E60F2324B061BA2298DF31E32D230D9F189C693E060DA0B83DC1FF894B5589065AA7630758DC513732096E0D9DDFA051E467E029A91B9DD6A793212585573D88280DAB9BA0CB73A43732B2D8E6C7D896D56E0E92F60B209968E076A78E14965BC9C38B22B07D49DD75

{"value":"foo"}