title: how to bind knockout's Observable array length to an html element
body: <p>Supose I have the following viewmodel</p>
  
  <pre><code>var ViewModel = function() {
     this.fruits = ko.observableArray(["Apple", "banana", "orange"]);
  };
  ko.applyBindings(new ViewModel());
  </code></pre>
  
  <p>I want to be able to do something like this to bind the observable array's length on the html like any other viewmodel property.</p>
  
  <pre><code>&lt;span data-bind="text: fruits.length"&gt;&lt;/span&gt;
  </code></pre>
  
  <p>For this purpuse, I tried converting observable array to simple array, but with no success</p>
  
  <pre><code>span data-bind="text: fruits().length"&gt;&lt;/span&gt;
  </code></pre>
  
  <p>I understand this should be easy and therefore must be missing something. Could you please point me in the right direction.</p>