title: Knockout.JS: Triggers based on changes in an observable
body: <p>I have an input element which is bound to a knockout observable:</p>
  
  <pre><code>&lt;input type="text" data-bind="value: myText, valueUpdate: 'keyup'" /&gt;
  </code></pre>
  
  <p>This updates the observable on each keyup. I now want to trigger additional events when the value changes. </p>
  
  <p>The following does this in principle:</p>
  
  <pre><code>this.myTextTrigger = ko.computed( function () {
      console.log( this.myText() );
  }, this );
  </code></pre>
  
  <p>However, it seems somewhat clunky. It also triggers on the initial instantiation of the template, where I only want to handle changes after that.
  Is there an official/easier way to trigger events based on changes to observables?</p>