Html程序  |  22行  |  317 B

<html>
<head>
<script>
window.addEventListener("message", messageReceived, false);

function messageReceived(event) {
  if (event.data === 'msg4') {
    window.top.document.title = event.data;
  } else {
    event.source.postMessage("2-1-reply", "*");
  }
}
</script>
</head>
<body>

Frame 2-1.
<br>

</body>
</html>