.removeProp，$para.append，$para.prop
<!DOCTYPE html>
<html>
<head>
<style>
img { padding:10px; }
div { color:red; font-size:24px; }
</style>
<script src="http://code.jquery.com/jquery-git.js"></script>
</head>
<body>
<p></p>
<script>
var $para = $("p");
$para.prop("luggageCode", 1234);
$para.append("The secret luggage code is: ", String($para.prop("luggageCode")), ". ");
$para.removeProp("luggageCode");
$para.append("Now the secret luggage code is: ", String($para.prop("luggageCode")), ". ");
</script>
</body>
</html>