HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>changedTouches</title>
  <style>
    #pad {
      width: 260px; height: 120px; border: 2px solid #333;
      display: flex; align-items: center; justify-content: center;
      touch-action: none; background: #f5f5f5;
    }
  </style>
</head>
<body>
  <div id="pad">Multi-touch then cancel</div>
  <p><button type="button" id="sim">Simulate ids 0</button></p>
  <pre id="out">waiting…</pre>
  <script>
    var pad = document.getElementById("pad");
    var out = document.getElementById("out");
    function showIds(list) {
      var ids = [];
      for (var i = 0; i < list.length; i++) ids.push(list[i].identifier);
      out.textContent = "canceled ids: " + ids.join(", ");
    }
    pad.addEventListener("touchcancel", function (event) {
      showIds(event.changedTouches);
    });
    document.getElementById("sim").onclick = function () {
      showIds([{ identifier: 0 }]);
    };
  </script>
</body>
</html>

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Element touchcancel — changedTouches (Try It)