title: Strange behaviour of knockout visibility binding
body: <p>My problem is rather strange. I use <code>ko.observable()</code> to set visibility of loading indicator on page like this:</p>
  
  <pre><code>&lt;img src="/images/loader.gif" data-bind="visible: isLoading"/&gt;
  </code></pre>
  
  <p>ViewModel:</p>
  
  <pre><code>self.processExcelData = function(data, event) {
          self.isLoading(true)
  
          ko.utils.arrayForEach(self.someBigArray(), function(item){
              // continuous stuff
          })
  
          self.isLoading(false)
  }
  </code></pre>
  
  <p>The problem is that although <code>isLoading</code> is actually <code>true</code> while <code>arrayForEach</code> iterates but loader is shown only after <code>arrayForEach</code> is finished. </p>