PostMessage in HTML5 implements cross-domain code analysis

127.0.0.1   localhost
127.0.0.1   main.com
127.0.0.1   A.com
127.0.0.1   B.com

    <h1 id="This-nbsp-is-nbsp-the-nbsp-main-nbsp-domain">This is the main domain</h1>
    <div style="margin:0 20px;">
        <textarea name="main" cols="80" rows="5"></textarea><br/>
        <input type="button" value="send to iframe A"/>
        <input type="button" value="send to iframe B"/>
    </div>
    <div style="float:left; margin:0 20px;">
        <h3 id="iframe-nbsp-A">iframe A</h3>
        <iframe src="http://a.com:8090/subAdomain.html" frameborder="1" style="width:300px; height:300px;"></iframe>
    </div>
    <div style="float:left;">
        <h3 id="iframe-nbsp-B">iframe B</h3>
        <iframe src="http://b.com:8090/subBdomain.html" frameborder="1" style="width:300px; height:300px;"></iframe>
    </div>
    <div style="float:left;">
        <h5 id="received"></h5>
    </div>
    <script>
        var received = document.querySelector(&#39;#received&#39;);
        var sendToIframeA = document.querySelectorAll(&#39;input&#39;)[0];
        var sendToIframeB = document.querySelectorAll(&#39;input&#39;)[1];
        var iframeA = document.querySelectorAll(&#39;iframe&#39;)[0];
        var iframeB = document.querySelectorAll(&#39;iframe&#39;)[1];
 
        //receive message
        function getMessage(e){
            console.log(&#39;main received!&#39;);
            received.innerHTML = &#39;Receive message from &#39; + e.origin + &#39;, the data is &#39; + e.data;
            e.source.postMessage(&#39;Received the message&#39;, e.origin);
        }
        window.addEventListener(&#39;message&#39;, getMessage, false);
 
        //post message
        sendToIframeA.addEventListener(&#39;click&#39;, function(){
            var content = document.querySelector(&#39;textarea&#39;).value;
            iframeA.contentWindow.postMessage(content, &#39;http://a.com:8090&#39;);
        }, false);
        sendToIframeB.addEventListener(&#39;click&#39;, function(){
            var content = document.querySelector(&#39;textarea&#39;).value;
            iframeB.contentWindow.postMessage(content, &#39;http://b.com:8090&#39;);
        }, false);
    </script>

       <h5 id="This-nbsp-is-nbsp-domain-nbsp-A">This is domain A</h5>
    <textarea name="subA" cols="30" rows="10"></textarea>
    <input type="button" value="send to parent"/>
    <div style="float:left;">
        <h5 id="received"></h5>
    </div>
    <script>
        var send = document.querySelector(&#39;input&#39;);
        var text = document.querySelector(&#39;textarea&#39;);
        var received = document.querySelector(&#39;#received&#39;);
 
        //receive message
        function getMessage(e){
            console.log(&#39;A received!&#39;);
            received.innerHTML = &#39;Receive message from &#39; + e.origin + &#39;, the data is &#39; + e.data;
            //e.source.postMessage(&#39;Received the message&#39;, e.origin);
        }
        window.addEventListener(&#39;message&#39;, getMessage, false);
 
        //post message
        send.addEventListener(&#39;click&#39;, function(){
            var content = text.value;
            window.parent.postMessage(content, &#39;http://main.com:8090&#39;);
        }, false);
    </script>

    <h5 id="This-nbsp-is-nbsp-domain-nbsp-B">This is domain B</h5>
    <textarea name="subB" cols="30" rows="10"></textarea>
    <input type="button" value="send to parent"/>
    <div style="float:left;">
        <h5 id="received"></h5>
    </div>
    <script>
        var send = document.querySelector(&#39;input&#39;);
        var text = document.querySelector(&#39;textarea&#39;);
        var received = document.querySelector(&#39;#received&#39;);
 
        //receive message
        function getMessage(e){
            console.log(&#39;B received!&#39;);
            received.innerHTML = &#39;Receive message from &#39; + e.origin + &#39;, the data is &#39; + e.data;
            //e.source.postMessage(&#39;Received the message&#39;, e.origin);
        }
        window.addEventListener(&#39;message&#39;, getMessage, false);
 
        //post message
        send.addEventListener(&#39;click&#39;, function(){
            var content = text.value;
            window.parent.postMessage(content, &#39;http://main.com:8090&#39;);
        }, false);
    </script>