blocks|key|1449306|text|尝试使用jquery's+ajax+functions|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1449307|entityMap|0|LINK|mutability|MUTABLE|url|http://api.jquery.com/jQuery.ajax/^0|4|N|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

try using <a href="http://api.jquery.com/jQuery.ajax/" rel="nofollow">jquery's ajax functions</a>

blocks|key|3516193|text|当您执行.html()时，浏览器会给出格式整齐的HTML。也就是说，所有的标签都是封闭的，所有的属性都用引号括起来，诸如此类。而且您从msgs.php返回的内容很可能没有完全格式化。因此，这就是区别所在。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3516194|然而，如果你担心效率低下，这种方法仍然是非常低效的。我的意思是，是的，您不再不必要地更新UI，但是您仍然从服务器加载消息列表，不是吗？|3516195|为了在这里节省几个字节，您应该使用"if-modified“技术。也就是说，与消息列表一起返回某种类型的时间戳。比方说，就是一个整数。当服务器上发生变化时，将该整数加1。当从服务器请求更新时，让AJAX代码传递之前接收到的时间戳，如果时间戳是当前的，则让服务器响应"nothing+changed“。否则，让服务器传输新的消息列表。粗略地说，这就是我们的想法。|3516196|entityMap^0|4|7|1V|8|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

When you do <code>.html()</code>, the browser gives you neatly formatted HTML. That is, all tags closed, all attributes in quotes, that sort of thing. And what you're returning from <code>msgs.php</code> is, most likely, not formatted perfectly. Hence, the difference.

If you're worried about inefficiency, however, this method would still be pretty inefficient. I mean, yes, you don't update the UI needlessly anymore, but you're still loading the list of messages from the server, don't you?

In order to save a couple of bytes here, you should rather have employed the "if-modified" technique. That is, along with the list of messages, return some kind of timestamp. Say, just an integer. When something changes on the server, increase that integer by one. When requesting an update from the server, have your AJAX code pass the previous received timestamp, and then have the server respond "nothing changed" if the timestamp is current. Otherwise, have the server transmit the new list of messages. This is, roughly, the idea.

blocks|key|1449529|text|我只使用jQuery的AJAX函数。它们让一切变得非常简单：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1449530|function+loadMsgs()
{
++++jQuery.get("msgs.php",+function(data)
++++{
++++++++if+($("#msgs").html()+!=+data)+
++++++++{
++++++++++++$("#msgs").html(data);
++++++++}+else+{
++++++++++++$("#msgs").html("EQUAL!");+//+only+here+for+testing
++++++++}
++++});
}|code-block|syntax|javascript|1449531|如果你真的想知道你的方法不工作的原因，你不需要检查服务器是否真的向你发送了一个响应(返回一个4的readyState+)：|offset|length|style|CODE|1449532|function+loadMsgs()
{
var+v_loadMsgs+=+new+XMLHttpRequest();

v_loadMsgs.open("GET",+"msgs.php");

v_loadMsgs.onreadystatechange+=+function()
{
++++if+(v_loadMsgs.readyState+==+4)
++++{
++++++++var+old_content+=+$("#msgs").html();
++++++++var+new_content+=+v_loadMsgs.responseText;

++++++++if+(old_content+!=+new_content)+
++++++++{
++++++++++++$("#msgs").html(new_content);
++++++++}

++++++++if+(old_content+==+new_content)+
++++++++{
++++++++++++$("#msgs").html("EQUAL!");+//+only+here+for+testing
++++++++}
++++}
};

v_loadMsgs.send(null);
}|1449533|entityMap^0|0|0|1A|1|1C|A|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|P|$]]

I'd just use jQuery's AJAX functions. They make everything really simple:

<pre><code>function loadMsgs()
{
 jQuery.get("msgs.php", function(data)
 {
 if ($("#msgs").html() != data) 
 {
 $("#msgs").html(data);
 } else {
 $("#msgs").html("EQUAL!"); // only here for testing
 }
 });
}
</code></pre>

If you really want to know why your method isn't working, you're not checking if the server actually sent you a response (which returns a <code>readyState</code> of <code>4</code>):

<pre><code>function loadMsgs()
{
var v_loadMsgs = new XMLHttpRequest();

v_loadMsgs.open("GET", "msgs.php");

v_loadMsgs.onreadystatechange = function()
{
 if (v_loadMsgs.readyState == 4)
 {
 var old_content = $("#msgs").html();
 var new_content = v_loadMsgs.responseText;

 if (old_content != new_content) 
 {
 $("#msgs").html(new_content);
 }

 if (old_content == new_content) 
 {
 $("#msgs").html("EQUAL!"); // only here for testing
 }
 }
};

v_loadMsgs.send(null);
}
</code></pre>

I have an online chat room that uses jQuery/Ajax for requesting data from the server. However, the method I use is very inefficient and I'm trying to improve it by only loading the server data if the chat content has been changed (new message, etc.) The method seems to be logically correct, although somehow it never evaluates to true. I've attached the code below, please tell me what I'm doing wrong as this is giving me a very hard time. I want the chat div to be changed only when the data from the server is different.

<pre><code>function loadMsgs()
{
var v_loadMsgs = new XMLHttpRequest();

v_loadMsgs.open("GET", "msgs.php");

v_loadMsgs.onreadystatechange = function()
{
 var old_content = $("#msgs").html();
 var new_content = v_loadMsgs.responseText;

 if (old_content != new_content) 
 {
 $("#msgs").html(new_content);
 }

 if (old_content == new_content) 
 {
 $("#msgs").html("EQUAL!"); // only here for testing
 }
};

v_loadMsgs.send(null);
}
</code></pre>

What is wrong with this jQuery/Ajax function?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个在线聊天室，它使用jQuery/Ajax从服务器请求数据。然而，我使用的方法效率非常低，我试图通过仅在聊天内容发生更改(新消息等)时加载服务器数据来改进它。该方法似乎在逻辑上是正确的，尽管不知何故它从不计算为true。我已经附上了下面的代码，请告诉我我做错了什么，因为这给了我一个非常艰难的时间。我希望仅当来自服...

问这个jQuery/Ajax函数有什么问题？
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