title: Why zoom level returns decimal?
body: <p>I use openlayers 6 in my project.
  Layers on the map hide/show acording to zoom level.</p>
  
  <p>Here is map and view defenitions:</p>
  
  <pre class="lang-js prettyprint-override"><code>view = new View({
      center: mapCenter,
      projection: israeliTM.getCode(),
      zoom: 0,
      resolutions: resolutions // resolutions array 
  });
  
  map = new Map({
      layers: layers,
      target: 'map',
      view: view
  });
  </code></pre>
  
  <p>This row is fired when zoom is changed:</p>
  
  <pre class="lang-js prettyprint-override"><code>var curRes = map.getView().getResolution()[map.getView().getZoom()];
  </code></pre>
  
  <p>As you can see on view defenition resolutions defined as array and when zoom is changed 
  I expect to get from this <code>map.getView().getZoom()</code> integer number that displays index in 
  resolutions array and return current resolution. In general it works as expected but sometimes
  <code>map.getView().getZoom()</code> returns decimal number like 3.56989.</p>
  
  <p>Any idea why <code>map.getView().getZoom()</code> returns some time decimal? </p>