HTML Code

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>subscribe check first</title>
</head>
<body>
  <button id="run">Enable Push</button>
  <pre id="out">Click Enable Push (needs HTTPS or localhost).</pre>
  <script>
    function urlBase64ToUint8Array(base64String) {
      var padding = "=".repeat((4 - (base64String.length % 4)) % 4);
      var base64 = (base64String + padding).replace(/-/g, "+").replace(/_/g, "/");
      var raw = atob(base64);
      return Uint8Array.from([].map.call(raw, function (c) { return c.charCodeAt(0); }));
    }
    document.getElementById("run").addEventListener("click", async function () {
      var out = document.getElementById("out");
      if (!window.isSecureContext || !("serviceWorker" in navigator)) {
        out.textContent = "Need secure context + serviceWorker.";
        return;
      }
      var vapid = "BEl62iUYgUivxIkv69yViEuiBIa-Ib9-SkvMeAtA3LFgDzkrxZJjSgSnfckjBJuBkr3qBUYIHBQFLXYp5Nksh8U";
      var sw = "self.addEventListener('install',function(e){self.skipWaiting();});self.addEventListener('activate',function(e){e.waitUntil(self.clients.claim());});";
      var url = URL.createObjectURL(new Blob([sw], { type: "application/javascript" }));
      try {
        await navigator.serviceWorker.register(url);
        var registration = await navigator.serviceWorker.ready;
        var pm = registration.pushManager;
        var subscription = await pm.getSubscription();
        if (!subscription) {
          subscription = await pm.subscribe({
            userVisibleOnly: true,
            applicationServerKey: urlBase64ToUint8Array(vapid)
          });
        }
        out.textContent = "Active subscription: " + subscription.endpoint;
      } catch (err) {
        out.textContent = "Error: " + err.message;
      }
      URL.revokeObjectURL(url);
    });
  </script>
</body>
</html>

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