var C = (function () {
    function C() {
        this.v = 1;
    }
    C.prototype.f = function () {
        console.log('v=' + this.v);
    };
    return C;
})();

var c = new C();

c.f();

var cSerializedCopy = JSON.parse(JSON.stringify(c));

cSerializedCopy.f();

v=1

.../test.js:17
cSerializedCopy.f();
                ^
TypeError: Object #<Object> has no method 'f'
    at Object.<anonymous> (.../test.js:17:17)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:901:3

function wasConstructed(obj) {
    var c = obj.constructor;
    return !(c === Object || c === Array ||
             c === Number || c === String ||
             c === Boolean);
}

// Returns the name of fn if fn is a function, or null otherwise
function getFuncName(fn) {
    var funcNameRegex = /^s*functions*([^(]*)(/,
        results = funcNameRegex.exec(fn.toString());
    return (results && results.length > 1) ? results[1] : null;
}

function getConstructorName(obj) {
    return getFuncName(obj.constructor);
}

var d = new Date();
var cName = getConstructorName(d); // returns "Date"

function getConstructorName(obj)
{
    return obj.constructor.name;
}

// I am going to use a Gizmo class to demonstrate my point
function Gizmo(prop1, prop2, prop3) {
  this.prop1 = prop1;
  this.prop2 = prop2;
  this.prop3 = prop3;

  // Now, this will flag what kind of object I have
  this.isGizmo = true;
}

// Make the object
var myGizmo = new Gizmo("The cat", "Thing 1", "Thing 2");

// Serialize the object
var gizmoJson = JSON.stringify(myGizmo);
console.log(gizmoJson);

// Now, go to rebuild the object:
var rawObject = JSON.parse(gizmoJson);

// Note that rawObject needs revived.
console.log("Checking if rawObject is a Gizmo: ");
console.log(rawObject instanceof Gizmo);

if (rawObject.isGizmo) {
  var myGizmo2 = new Gizmo(rawObject.prop1, rawObject.prop2, rawObject.prop3);

  console.log(myGizmo2);
  console.log("Checking if myGizmo2 is a Gizmo: ");
  console.log(myGizmo2 instanceof Gizmo);
}

c instanceof C // true

cSerializedCopy instanceof C // false