假設有兩個網頁：aaa.jsp和bbb.jsp，然後從AAA.jsp傳輸資料到BBB.jsp內。
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aaa.jsp的內容：
<%@ page language="java" contentType="text/html; charset=BIG5" pageEncoding="BIG5"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=BIG5">
<title>AAA</title>
</head>
<script type="text/javascript">
function sendMessage()
{
var menu = document.getElementById( "bbbID" ).contentWindow;
menu.postMessage( document.getElementById( "messageID" ).value, 'http://localhost:8080' );
}
</script>
<body>
<iframe src = "bbb.jsp" id = "bbbID" frameborder = "1" scrolling = "auto"></iframe>
<form>
<input type = "text" id = "messageID" value = "">
<input type = "button" value = "傳送訊息給bbb" onclick = "sendMessage()">
</form>
</body>
</html>
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bbb.jsp的內容：
<%@ page language="java" contentType="text/html; charset=BIG5" pageEncoding="BIG5"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=BIG5">
<title>Insert title here</title>
</head>
<script type="text/javascript">
function getMessage( event )
{
if( event.origin != 'http://localhost:8080' )
{
alert( event.origin );
return;
}
document.getElementById( "receiveID" ).innerHTML = event.data;
}
if( typeof window.addEventListener != 'undefined' )
{
window.addEventListener( 'message', getMessage, false );
}
else if( typeof window.attachEvent != 'undefined' )
{
window.attachEvent( 'onmessage', getMessage );
}
</script>
<body>
<h1>這是bbb！</h1>
<div id = "receiveID">等待接收訊息！</div>
</body>
</html>
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aaa.jsp內的postMessage有兩個參數，前面是要夾帶的資料，後面是傳送的網域；然後在bbb.jsp內可以用event.origin來判斷網域是否相符，是個保險機制。如果不需要這層保險機制，可以將後面的參數設為'*'，這樣接收端也可以不用進行檢查。
例如在aaa.jsp內將
menu.postMessage( document.getElementById( "messageID" ).value, 'http://localhost:8080' );
改為
menu.postMessage( document.getElementById( "messageID" ).value, '*' );
然後在bbb.jsp內將
function getMessage( event )
{
if( event.origin != 'http://localhost:8080' )
{
alert( event.origin );
return;
}
document.getElementById( "receiveID" ).innerHTML = event.data;
}
改為
function getMessage( event )
{
document.getElementById( "receiveID" ).innerHTML = event.data;
}
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而之所以會同時使用addEventListener和attachEvent，是因為以前各大瀏覽器不一定會支援addEventListener，現在如何我是不知道啦......因此先檢查addEventListener能不能用，不行再用attachEvent。
網路上可找到許多關於addEventListener和attachEvent的詳細解釋，不需要我這個外行人做粗淺的說明了。
