I have a Model object that needs converted to a JSON object for passing to a WebAPI and when I call the .toJSON method a valid JSON object is returned, but Dates are still in a Date format, which they are not being properly serialized to JSON. So I have for the meantime added a prototype method to the ObservableObject called toJSON2 that checks if the field being processed is a Date object to call the Date objects toJSON method which is a prototype method you guys created anyways. It would be nice though if this one condition to check if the field being processed is a Date to then convert to a JSON date could be added into your source code.
kendo.data.ObservableObject.prototype.toJSON2 = function () { var result = {}, value, field; for (field in this) { if (this.shouldSerialize(field)) { value = this[field]; if (value instanceof kendo.data.ObservableObject || value instanceof kendo.data.ObservableArray) { value = value.toJSON2(); } else if (value instanceof Date) { value = value.toJSON(); } result[field] = value; } } return result;}