How to parse HTML input string

var value = document.getElementById('myinput').value;
        var obj = JSON.parse(value);
        var lat = obj.lat;
        var long = obj.lon;

public class Geo
       {
           public string lat { get; set; }
           public string lon { get; set; }
       }

JavaScriptSerializer js = new JavaScriptSerializer();
         string json = myinput.Value;
         var data = js.Deserialize<Geo>(json);
         var lat = data.lat;
         var lon = data.lon