Get mousewheel distance in pixels

Even with support for the "wheel" event's deltaY, getting the actual distance scrolled is inconsistent and a pain. This fiddle demonstrates getting it by just seeing how far the browser interprets the scroll in pixels.

by IceCreamYou

HTML

<div id=wrpr>
  <canvas id=cvs></canvas>
  <div id=scrl>
    <div id="inner"></div>
  </div>
</div>
<div id=log></div>

CSS

#wrpr {
  position: relative;
  width: 300px;
  overflow: hidden;
}
#cvs {
  background-color: red;
  width: 300px;
  height: 200px;
  position: relative;
  z-index: 1;
}
#scrl {
  background-color: rgba(0, 0, 255, 0.5);
  padding-right: 100px;
  position: absolute;
  width: 300px;
  height: 200px;
  top: 0;
  left: 0;
  overflow-y: auto;
  overflow-x: hidden;
  z-index: 0;
}
#inner {
  width: 300px;
  height: 16384px;
}

JavaScript

var scroller = document.getElementById('scrl'),
	logElem = document.getElementById('log'),
  timerId = -1,
  timerFn = function() {
  	scroller.style.zIndex = 0;
  };
scroller.scrollTop = 8192;
scroller.addEventListener('wheel', function(event) {
	log([event.deltaMode, Math.round(event.deltaY), scroller.scrollTop - 8192])
  scroller.scrollTop = 8192;
  clearTimeout(timerId);
  timerId = setTimeout(timerFn, 100);
  //event.preventDefault();
});

document.getElementById('cvs').addEventListener('wheel', function(event) {
	log([event.deltaMode, Math.round(event.deltaY)]);
  scroller.style.zIndex = 1;
  timerId = setTimeout(timerFn, 100);
  event.preventDefault();
});

function log(s) {
	var d = document.createElement('div');
  d.textContent = typeof s === 'string' ? s : JSON.stringify(s);
  logElem.insertBefore(d, logElem.firstChild);
}