JAVASCRIPT

Form serialize to JSON

function onSubmit( form ){
  var data = JSON.stringify( $(form).serializeArray() ); //  <-----------

  console.log( data );
  return false; //don't submit
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<form onsubmit='return onSubmit(this)'>
  <input name='user' placeholder='user'><br>
  <input name='password' type='password' placeholder='password'><br>
  <button type='submit'>Try</button>
</form>

serialize object to json

Product product = new Product();
product.ExpiryDate = new DateTime(2008, 12, 28);

JsonSerializer serializer = new JsonSerializer();
serializer.Converters.Add(new JavaScriptDateTimeConverter());
serializer.NullValueHandling = NullValueHandling.Ignore;

using (StreamWriter sw = new StreamWriter(@"c:json.txt"))
using (JsonWriter writer = new JsonTextWriter(sw))
{
    serializer.Serialize(writer, product);
    // {"ExpiryDate":new Date(1230375600000),"Price":0}
}