title: How to detect device orientation with JavaScript?
body: <p>I've seen a number of ways to detect the screen orientation of the device, including using a check to test innerWidth versus innerHeight, like so.</p>
  
  <pre><code>function getOrientation(){
      var orientation = window.innerWidth &gt; window.innerHeight ? "Landscape" : "Primary";
      return orientation;
  }
  </code></pre>
  
  <p>But what if I want to check for <em>changes</em> in screen orientation as well with an event listener? I've tried this code but it doesn't work for me.</p>
  
  <pre><code>  function doOnOrientationChange()
    {
      switch(window.orientation) 
      {  
        case -90:
        case 90:
          alert('landscape');
          break; 
        default:
          alert('portrait');
          break; 
      }
    }
  
    window.addEventListener('orientationchange', doOnOrientationChange);
  
    // Initial execution if needed
    doOnOrientationChange();
  </code></pre>
  
  <p>It doesn't detect device orientation, and the listener does not register for me (I'm using Chrome's device emulator).</p>