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Detailed explanation of message communication code in HTML5

零下一度Original: 2017-04-22 14:38:511818browse

HTML5 supports cross-document messaging (Cross-Document Messaging).

Since message communication is used, events must occur. According to the generation and consumption of events, we can find the sender and receiver, that is, Sender and Listener.

Litener needs to do the following work:

Write a message processing function;
Register the message processing function: addEventListener('message', function, false);

The Sender needs to do the following:

postMessage('this is a message' , 'http://www.php.cn');

Members contained in the event object event include:

data: passed Data;
origin: origin, origin includes three elements: host, protocol, port;
source: source object;

Okay, let’s look at an example. This example shows nesting pages within pages and sending messages to child pages:

The parent page is as follows:

<!DOCTYPE html>
<html lang="en">

<!-- 
    crossDomain.html by Bill Weinman 
    <http://bw.org/contact/>
    created 2011-04-16

    Copyright (c) 2011 The BearHeart Group, LLC
    This file may be used for personal educational purposes as needed. 
    Use for other purposes is granted provided that this notice is
    retained and any changes made are clearly indicated as such. 
-->

<head>
    <title>
        HTML5 Messaging Template File (One)
    </title>
    <link rel="stylesheet" type="text/css" href="../CSS/main.css">
    <style>
        #frameTwo {
            float: left;
            width: 500px;
            height: 400px;
            margin: 0 5px;
            padding: 3px;
            border-top: 2px solid #3c6b92;
            border-left: 2px solid #3c6b92;
            border-bottom: 2px solid #ccc;
            border-right: 2px solid #ccc;
        }
        #content { height: 500px; }
    </style>
    <script type="text/javascript">
		// 域名
        var originTwo = &#39;http://two.3sn.net&#39;;
		// URL地址
        var URLTwo = &#39;http://two.3sn.net/H5Msg/ExerciseFiles/Chap01/crossDomainTwo.html&#39;;
        var windowTwo = null;

        function handleMessage(event) {
			// 判断源区域
            if (event.origin == originTwo) {
                if(!windowTwo) windowTwo = event.source;
                log(&#39;message from origin: &#39; + event.origin);
                log(event.data);
				// 发送消息
                windowTwo.postMessage(&#39;this is from windowOne!&#39;, originTwo);
                log(&#39;message sent back to windowTwo&#39;);
            } else {
                dispError(&#39;message from untrusted origin: &#39; + event.origin);
            }
        }


        function init() {
			// 添加消息处理函数
		    window.addEventListener("message", handleMessage, false);
            window.onerror = windowErrorHandler;
            log(&#39;this is windowOne&#39;);
            log(&#39;host: &#39; + location.host);
			
			// load two页面
            element(&#39;frameTwo&#39;).src = URLTwo;   // load the frame
        }

        // ##### Utilities #####

        // shortcut for getElementById
        function element(id) { return document.getElementById(id); }

        function clearDisp() {
            element(&#39;pageResults&#39;).innerHTML = &#39;&#39;;
            element(&#39;message&#39;).innerHTML = &#39;&#39;;
            element(&#39;message&#39;).className = &#39;&#39;;
        }

        function dispMessage(message) {
            m = element(&#39;message&#39;);
            m.className = &#39;message&#39;;
            if(m.textContent.length > 0) {
                m.innerHTML += &#39;<br />&#39; + message;
            } else m.innerHTML = message;
        }

        function windowErrorHandler(message, filename, lineno) {
            dispError(message + &#39; (&#39; + filename + &#39;:&#39; + lineno + &#39;)&#39; );
            return true;
        };

        function dispError(errorMessage) {
            element(&#39;pageResults&#39;).innerHTML += 
                errorMessage ? &#39;<p class="error">&#39; + errorMessage + &#39;</p>\n&#39; : &#39;&#39;;
        }

        function log(m) {
            if(m.length < 1) return;
            logElement = element(&#39;log&#39;);
            if(logElement.textContent.length > 0) logElement.innerHTML += &#39;<br />&#39;;
            logElement.innerHTML += nowTimeString() + &#39; &#39; + m;
        }

        function nowTimeString() {
            var d = new Date();
            return numToString(d.getUTCHours(), 2) + &#39;:&#39; + numToString(d.getUTCMinutes(), 2) + &#39;:&#39; +
                numToString(d.getUTCSeconds(), 2) + &#39;.&#39; + numToString(d.getUTCMilliseconds(), 3);
        }

        function numToString( num, len ) {
            var num = num + &#39;&#39;;
            while(num.length < len) num = &#39;0&#39; + num;
            return num;
        }

        window.onload = init;

    </script>
</head>

<body>

<p id="content">

    <h1> 
        HTML5 Messaging Template File (One)
    </h1>

    <p id="message"></p>
    <p id="pageResults"></p>

    <iframe id="frameTwo">
        <p>Your browser doesn&#39;t support the iFrame feature</p>
    </iframe>

    <p id="log" style="font-family: monospace"></p>

</p>
</body>
</html>

<!DOCTYPE html>
<html lang="en">

<!-- 
    crossDomain.html by Bill Weinman 
    <http://bw.org/contact/>
    created 2011-04-16

    Copyright (c) 2011 The BearHeart Group, LLC
    This file may be used for personal educational purposes as needed. 
    Use for other purposes is granted provided that this notice is
    retained and any changes made are clearly indicated as such. 
-->

<head>
    <title>
        HTML5 Messaging Template File (Two)
    </title>
    <link rel="stylesheet" type="text/css" href="../CSS/main.css">
    <script type="text/javascript">
        var originOne = &#39;http://one.3sn.net&#39;;

        function handleMessage(event) {
            if (event.origin == originOne) {
                log(&#39;message from origin: &#39; + event.origin);
                log(event.data);
            } else {
                dispError(&#39;message from untrusted origin: &#39; + event.origin);
            }
        }

        // ##### Init #####

        function init() {
            window.onerror = windowErrorHandler;    // addEventListener doesn&#39;t provide the right error object in Firefox
            window.addEventListener("message", handleMessage, false);
            log(&#39;this is windowTwo&#39;);
            log(&#39;host: &#39; + location.host);
            var windowOne = parent;
            windowOne.postMessage(&#39;this is from windowTwo!&#39;, originOne);
            log(&#39;message sent to windowOne&#39;);
        }

        // ##### Utilities #####

        // shortcut for getElementById
        function element(id) { return document.getElementById(id); }

        function clearDisp() {
            element(&#39;pageResults&#39;).innerHTML = &#39;&#39;;
            element(&#39;message&#39;).innerHTML = &#39;&#39;;
            element(&#39;message&#39;).className = &#39;&#39;;
        }

        function dispMessage(message) {
            m = element(&#39;message&#39;);
            m.className = &#39;message&#39;;
            if(m.textContent.length > 0) {
                m.innerHTML += &#39;<br />&#39; + message;
            } else m.innerHTML = message;
        }

        function windowErrorHandler(message, filename, lineno) {
            dispError(message + &#39; (&#39; + filename + &#39;:&#39; + lineno + &#39;)&#39; );
            return true;
        };

        function dispError(errorMessage) {
            element(&#39;pageResults&#39;).innerHTML += 
                errorMessage ? &#39;<p class="error">&#39; + errorMessage + &#39;</p>\n&#39; : &#39;&#39;;
        }

        function log(m) {
            if(m.length < 1) return;
            logElement = element(&#39;log&#39;);
            if(logElement.textContent.length > 0) logElement.innerHTML += &#39;<br />&#39;;
            logElement.innerHTML += nowTimeString() + &#39; &#39; + m;
        }

        function nowTimeString() {
            var d = new Date();
            return numToString(d.getUTCHours(), 2) + &#39;:&#39; + numToString(d.getUTCMinutes(), 2) + &#39;:&#39; +
                numToString(d.getUTCSeconds(), 2) + &#39;.&#39; + numToString(d.getUTCMilliseconds(), 3);
        }

        function numToString( num, len ) {
            var num = num + &#39;&#39;;
            while(num.length < len) num = &#39;0&#39; + num;
            return num;
        }

        window.onload = init;

    </script>
</head>

<body>

<p id="content">

    <h1> 
        HTML5 Messaging Template File (Two)
    </h1>

    <p id="message"></p>
    <p id="pageResults"></p>
    <p id="log" style="font-family: monospace"></p>

</p>
</body>
</html>

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