Question

If I declare an object as follows:

var foo.bar = new Object;

Does that automatically make foo an object? If not and I want both foo and foo.bar to be objects do I need to use the following code:

var foo = new Object;
var foo.bar = new Object;

And if I create these two objects as above, is there a parent/child relationship between them or are they completely separate entities?

I apologize for the simple nature of my question, but I am trying to more fully understand the various ways data can be structured.

Answer 1

If I declare an object as follows:

  var foo.bar = new Object;

Does that automatically make foo an object?

No. It’s a syntax error;

SyntaxError: Unexpected token .

If not and I want both foo and foo.bar to be objects do I need to use the following code:

var foo = new Object;
var foo.bar = new Object;

No, that’s again a syntax error. You should be using.

var foo = new Object;
foo.bar = new Object;

But it’s more common to use object literal syntax these days;

var foo = {
    bar: {

    }
}

And if I create these two objects as above, is there a parent/child relationship between them or are they completely separate entities?

They are completely separate entities. The only link between them is that foo holds a reference to bar. Something else can easily hold a reference to bar;

var baz = foo.bar;
// Now baz and foo.bar are both pointing to the same object

alert(baz === foo.bar); // true;
baz.attr = 1;
alert(baz.attr); // 1
alert(foo.bar.attr); // 1

delete foo.bar; // delete foo's reference to bar
alert(baz.attr); // still shows 1
alert(foo.bar.attr); // error, because we deleted `bar`.

Try it yourself… http://jsfiddle.net/AMXLE/1