title: Property innerWidth does not exist on type EventTarget
body: <p>When I run a code:</p>
  
  <pre><code>public onResize(event: Event) {
      console.log(event.target.innerWidth);
  
      //--solution--
      //var w = event.target as Window;
      //console.log(w.innerWidth);
    }
  </code></pre>
  
  <p>I receive an error:</p>
  
  <pre><code>Property innerWidth does not exist on type EventTarget
  </code></pre>
  
  <p>I would like to avoid extending types in TypeScript (as it is described here <a href="https://stackoverflow.com/questions/42066421/property-value-does-not-exist-on-type-eventtarget">Property &#39;value&#39; does not exist on type &#39;EventTarget&#39;</a> ), so I cast <code>event.target</code> to <code>Window</code> class. I'm not sure if I cast to proper class. Which class should I cast to? How to find out a proper class which should be cast to?</p>