How to add code to a function outside of its main body?
<p>I want add code to a function, outside of the function and possibly even in an entirely different JS file. Is this possible? How can I do this? Here's a code snippet representing what I've tried so far:</p>

<pre><code>function myViewModel() {
    var self = this;

    this.firstName = ko.observable("Mike");
    this.lastName = ko.observable("Rassel");

    // this was where I was originally making the call
    //myViewModel.fullName = ko.computed(function() {
    //    return self.firstName() + ' ' + self.lastName();
    })
}

// this is where the error is happening 
myViewModel.fullName = ko.computed(function() {
    return self.firstName() + ' ' + self.lastName();

ko.applyBindings(new myViewModel());
</code></pre>

<p>More code can be viewed at <a href="http://jsfiddle.net/6E7Lq/" rel="nofollow">this JFiddle</a>.</p>
