title: DOM scroll (touchmove) event, how to find which element scrolls
body: <p>Here is the somewhat contrived code:</p>
  <pre><code> function h (evt) {
     if(evt.target.nodeName !=== 'POPUP') {
         evt.preventDefault()
     }
   }
   window.addEventListener('DOMMouseScroll', h, false)
   window.addEventListener('wheel', h, false)
  </code></pre>
  <p>What it tries to achieve here is to prevent all other scrolling on the page, except inside popup when popup is opened.
  But this doesn't work because <code>evt.target</code> contains element currently pointed by mouse rather than one that actually scrolled. So either the whole page would be scrolled or just popup conents, but in both cases <code>evt.target</code> will point to some button inside popup.</p>
  <p>But the idea is to get what got actually scrolled now, page body or popup.</p>
  <p><a href="https://jsfiddle.net/zr9hjL4s/1/" rel="nofollow noreferrer">https://jsfiddle.net/zr9hjL4s/1/</a></p>