HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>scroll rAF</title>
  <style>
    #scroll-box {
      overflow: auto; height: 120px; width: 200px;
      border: 2px solid #333;
    }
    #scroll-box .inner { height: 400px; padding: 8px; }
  </style>
</head>
<body>
  <div id="scroll-box"><div class="inner">Scroll quickly…</div></div>
  <pre id="out">(waiting)</pre>
  <script>
    var box = document.getElementById("scroll-box");
    var out = document.getElementById("out");
    var latestTop = 0;
    var ticking = false;
    function paint() {
      out.textContent = "rAF paint top=" + Math.round(latestTop);
      ticking = false;
    }
    box.addEventListener("scroll", function () {
      latestTop = box.scrollTop;
      if (!ticking) {
        requestAnimationFrame(paint);
        ticking = true;
      }
    });
  </script>
</body>
</html>

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Element scroll — requestAnimationFrame throttle (Try It)