I'm confused about javascript inheritance.

Consider the following code:

```
function parent(firstname, lastname) {
    this.firstname = firstname || "abc";
    this.lastname = lastname || "def";
}

function child() {
   this.childname = "xys";
}
parent.prototype.Greetings = function () {
    alert("sayhi");
}
child.prototype = Object.create(parent.prototype);
var child1 = new child();

```

Now, does the `child1` object have access to the `firstname` and `lastname` properties?
I can access the `Greetings` method (because it's in the prototype).
If I try to access these, it is showing as `undefined`. 
What changes have to be made to access these variables?