title: Unable to update span with observableArray length in Knockout.js
body: <p>I am new to KO and I have a question I cannot get around.</p>
  
  <p>I don't understand the theory behind observable in this particular part of my try out. I have a span that should always update it self with the value of an observableArray (self.links) which is filled by the user through a form.</p>
  
  <p>Everytime I push to the array I thought it should update automatically the span but it does not and I do not understand why, and that is my main issue, not understanding the why.</p>
  
  <p>I know that if instead of</p>
  
  <pre><code>&lt;div class="panel-heading"&gt;&lt;span data-bind="text: numberOfLinks"&gt;
  </code></pre>
  
  <p>I have...</p>
  
  <pre><code>&lt;div class="panel-heading"&gt;&lt;span data-bind="text: links().length"&gt;
  </code></pre>
  
  <p>the span will automatically update, but the question is, how do I actually put that links().length value into a variable so it can be used in other places (this will probably not happen but I am curious).</p>
  
  <p>I have here the js so it is easier: <a href="http://jsfiddle.net/Kc4vL/2/" rel="nofollow">http://jsfiddle.net/Kc4vL/2/</a></p>