HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>ariaValueNow vs attribute</title>
</head>
<body>
  <pre id="out"></pre>
  <script>
    var el = document.createElement("div");
    el.setAttribute("role", "slider");
    el.setAttribute("aria-valuenow", "1");
    document.body.insertBefore(el, document.getElementById("out"));
    el.ariaValueNow = "2";
    document.getElementById("out").textContent = JSON.stringify({
      fromProperty: el.ariaValueNow,
      fromAttribute: el.getAttribute("aria-valuenow"),
      same: el.ariaValueNow === el.getAttribute("aria-valuenow")
    }, null, 2);
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

Element.ariaValueNow — vs attribute (Try It)