title: Eventhandler model change in knockout.js
body: <p>I need to know (in JS) when my model (using knockout.js) or rather a propery has changed.</p>
  
  <p>How do I do that?</p>
  
  <p>Here some code:</p>
  
  <pre><code>function DrawingToolViewModel() {
      var self = this;
      self.drawMode = ko.observable('Line');
  }
  model = new DrawingToolViewModel();
  ko.applyBindings(model);
  </code></pre>
  
  <p>Now the assigned HTML element to drawMode will be updated by the model and back, whatever changes. That's fine, but how can I react in JS if something in the model has changed? </p>
  
  <p><strong>EDIT</strong></p>
  
  <p>My question wasn't clear enough, sorry. I know observables but I want to subscribe to ALL properties without doing that for every single property. More like "notify me if something in the model has changed"</p>