HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>activeViewTransition same ref</title>
  <style>
    body { font-family: sans-serif; margin: 1rem; }
    #panel { padding: 1rem; background: #dbeafe; border-radius: 8px; }
    #panel[data-state="b"] { background: #fde68a; }
    ::view-transition-old(root), ::view-transition-new(root) { animation-duration: 0.5s; }
  </style>
</head>
<body>
  <div id="panel" data-state="a">Panel state A</div>
  <button type="button" id="swap">Swap state</button>
  <pre id="out">Click Swap state.</pre>
  <script>
    var panel = document.getElementById("panel");
    document.getElementById("swap").addEventListener("click", function () {
      if (typeof document.startViewTransition !== "function") {
        document.getElementById("out").textContent = "Cannot compare — startViewTransition missing";
        return;
      }
      var vt = document.startViewTransition(function () {
        var next = panel.dataset.state === "a" ? "b" : "a";
        panel.dataset.state = next;
        panel.textContent = "Panel state " + next.toUpperCase();
      });
      document.getElementById("out").textContent = JSON.stringify({
        sameReference: document.activeViewTransition === vt,
        tip: "Store vt or re-read activeViewTransition later"
      }, null, 2);
    });
  </script>
</body>
</html>

Lines: 0 | Characters: 0

Live Preview Auto-refresh on Run

Document.activeViewTransition — same reference (Try It)