title: How to fix " Property 'wheelDelta' does not exist on type 'WheelEvent' " while upgrading to angular 7,rxjs6?
body: <p>I'm upgrading to angular7 with rxjs6: in <code>mouseWheelEvent</code> type I am getting <code>"Property 'wheelDelta' does not exist on type 'WheelEvent'"</code>.</p>
  
  <p>Do we have any alternative for <code>wheelDelta</code>?</p>
  
  <pre><code>mouseWheelFunc(event: MouseWheelEvent): void {
  
      //  var event = window.event || event; // old IE support
  
      let delta = Math.max(-1, Math.min(1, (event.wheelDelta || -event.detail)));
  
      if ( delta &gt; 0) {
        this.mouseWheelUp.emit(event);
      } else if ( delta &lt; 0) {
        this.mouseWheelDown.emit(event);
      }
  
      // for IE
      event.returnValue = false;
      // for Chrome and Firefox
      if ( event.preventDefault) {
        event.preventDefault();
      }
    }
  </code></pre>
  
  <blockquote>
    <p>ERROR in
    src/modules/components/numeric-stepper/mousewheel.directive.ts(23,49):
    error TS2339: Property 'wheelDelta' does not exist on type
    'WheelEvent'.</p>
  </blockquote>