index.html

<button id="scanButton">Scan</button>
<button id="writeButton">Write</button>

<audio src="/meow.wav" id="meow"></audio>

<script>
  scanButton.addEventListener("click", async () => {
    console.log("User clicked scan button");

    try {
      const ndef = new NDEFReader();
      await ndef.scan();
      console.log("> Scan started");

      ndef.addEventListener("readingerror", () => {
        console.log("Argh! Cannot read data from the NFC tag. Try another one?");
      });

      ndef.addEventListener("reading", ({ message, serialNumber }) => {
        console.log(`> Serial Number: ${serialNumber}`);
        console.log(`> Records: (${message.records.length})`);

        meow.play();
      });
    } catch (error) {
      console.log("Argh! " + error);
    }
  });

  writeButton.addEventListener("click", async () => {
    console.log("User clicked write button");

    try {
      const ndef = new NDEFReader();
      await ndef.write("Hello world!");
      console.log("> Message written");
    } catch (error) {
      console.log("Argh! " + error);
    }
  });
</script>