No, there is no build in way to deep clone objects.

And deep cloning is a difficult and edgey thing to deal with.

Lets assume that a method deepClone(a) should return a "deep clone" of b.

Now a "deep clone" is an object with the same [[Prototype]] and having all the own properties cloned over.

For each clone property that is cloned over, if that has own properties that can be cloned over then do so, recursively.

Of course were keeping the meta data attached to properties like [[Writable]] and [[Enumerable]] in-tact. And we will just return the thing if it's not an object.

Copyvar deepClone = function (obj) {
    try {
        var names = Object.getOwnPropertyNames(obj);
    } catch (e) {
        if (e.message.indexOf("not an object") > -1) {
            // is not object
            return obj;
        }    
    }
    var proto = Object.getPrototypeOf(obj);
    var clone = Object.create(proto);
    names.forEach(function (name) {
        var pd = Object.getOwnPropertyDescriptor(obj, name);
        if (pd.value) {
            pd.value = deepClone(pd.value);
        }
        Object.defineProperty(clone, name, pd);
    });
    return clone;
};

This will fail for a lot of edge cases.

Live Example

As you can see you can't deep clone objects generally without breaking their special properties (like .length in array). To fix that you have to treat Array seperately, and then treat every special object seperately.

What do you expect to happen when you do deepClone(document.getElementById("foobar")) ?

As an aside, shallow clones are easy.

CopyObject.getOwnPropertyDescriptors = function (obj) {
    var ret = {};
    Object.getOwnPropertyNames(obj).forEach(function (name) {
        ret[name] = Object.getOwnPropertyDescriptor(obj, name);
    });
    return ret;
};

var shallowClone = function (obj) {
    return Object.create(
        Object.getPrototypeOf(obj),
        Object.getOwnPropertyDescriptors(obj)
    );
};

You should use the library json2.js. It is the basis for the standard JSON.stringify(...) that some browsers include natively.

You can find the page it originated from here: https://github.com/douglascrockford/JSON-js/blob/master/json2.js

The script automatically makes sure it only adds a JSON.stringify(...) method if it doesn't already exist so there is no danger including it in a browser that has it.

You need to JSON.parse() your valid JSON string.

var str = '{"hello":"world"}';
try {
  var obj = JSON.parse(str); // this is how you parse a string into JSON 
  document.body.innerHTML += obj.hello;
} catch (ex) {
  console.error(ex);
}

JSON.stringify turns a JavaScript object into JSON text and stores that JSON text in a string, eg:

var my_object = { key_1: "some text", key_2: true, key_3: 5 };

var object_as_string = JSON.stringify(my_object);  
// "{"key_1":"some text","key_2":true,"key_3":5}"  

typeof(object_as_string);  
// "string"  

JSON.parse turns a string of JSON text into a JavaScript object, eg:

var object_as_string_as_object = JSON.parse(object_as_string);  
// {key_1: "some text", key_2: true, key_3: 5} 

typeof(object_as_string_as_object);  
// "object" 

Take a closer look at the two comments you've put onto the question:

I suppose after re-reading my question, I'm seeing that in my C# example, I'm serializing the XML and THEN converting the serialized object ToString();. There inlies the rub.

and

I guess for continuity, it would be better (for me) to have a method that looks like this... JSON.serialize(obj).toString(); or jsonObject().toString();... this way it would look much like my C#... but now I'm over complicating it.

Now remember that in Javascript, an object is a hash (rather, if using Prototype or another framework, it should be qualified as a "special kind of hash" - but the simple form works for this example):

var obj = {
   foo: 1,
   bar: function() { console.log(this.foo); }
}
obj.foo; // 1
obj.bar; // function reference
obj.bar(); // function call
obj['foo']; // 1
obj['bar']; // function reference
obj['bar'](); // function call

The only reason a serialize() might be necessary in Javascript is to cut out the functions, references to other objects, etc.

So, to go back to your C# example - we've just cut out .Serialize() as unnecessary. An object is a hash, it's already serialized, further "serialization" would have to be done manually in your own code anyway. All that leaves you is .ToString().

Does .stringify() make more sense now?