CSS的优先级

深藏阁楼爱情的钟 2022-07-29 10:41 147阅读 0赞

**样式的优先级**

多重样式（Multiple Styles）：如果外部样式、内部样式和内联样式同时应用于同一个元素，就是使多重样式的情况。

一般情况下，优先级如下：

（外部样式）External style sheet <（内部样式）Internal style sheet <（内联样式）Inline style

有个例外的情况，就是如果**外部样式**放在**内部样式**的**后面**，则外部样式将覆盖内部样式。

示例如下：

**选择器的优先权**

[![jc6\_002][jc6_002]][jc6_002_jc6_002]

**解释：**

1.  内联样式表的权值最高 1000；

2.  ID 选择器的权值为 100

3.  Class 类选择器的权值为 10

4.  HTML 标签选择器的权值为 1

利用选择器的权值进行计算比较，示例如下：

<table style="table-layout:fixed; word-wrap:break-word; border:0px none; border-collapse:collapse; word-break:break-word; padding:0px; width:699.091px"> 
 <tbody> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;html&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;head&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;style type="text/css"&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#redP&nbsp;p&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;权值&nbsp;=&nbsp;100+1=101&nbsp;*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;color:#F00;&nbsp;&nbsp;/*&nbsp;红色&nbsp;*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#redP&nbsp;.red&nbsp;em&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;权值&nbsp;=&nbsp;100+10+1=111&nbsp;*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;color:#00F;&nbsp;/*&nbsp;蓝色&nbsp;*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;#redP&nbsp;p&nbsp;span&nbsp;em&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;/*&nbsp;权值&nbsp;=&nbsp;100+1+1+1=103&nbsp;*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;color:#FF0;/*黄色*/</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;/style&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;/head&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;body&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;div&nbsp;id="redP"&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;p&nbsp;class="red"&gt;red</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;span&gt;&lt;em&gt;em&nbsp;red&lt;/em&gt;&lt;/span&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/p&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;p&gt;red&lt;/p&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/div&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;/body&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;/html&gt;</td> 
 </tr> 
 </tbody> 
</table>

**结果**： 标签内的数据显示为蓝色。

**CSS 优先级法则：**

A  选择器都有一个权值，权值越大越优先；

B  当权值相等时，后出现的样式表设置要优于先出现的样式表设置；

C  创作者的规则高于浏览者：即网页编写者设置的CSS 样式的优先权高于浏览器所设置的样式；

D  继承的CSS 样式不如后来指定的CSS 样式；

E  在同一组属性设置中标有“!important”规则的优先级最大；示例如下：

**结果**：在Firefox 下显示为**蓝色**；在IE  6 下显示为**红色**；

**使用脚本添加样式**

当在连接外部样式后，再在其后面使用JavaScript 脚本插入内部样式时（即内部样式使用脚本创建），IE 浏览器就表现出它的另类了。代码如下：

<table style="table-layout:fixed; word-wrap:break-word; border:0px none; border-collapse:collapse; word-break:break-word; padding:0px; width:699.091px"> 
 <tbody> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;html&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;head&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;title&gt;&nbsp;demo&nbsp;&lt;/title&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;meta&nbsp;name="Author"&nbsp;content="xugang"&nbsp;/&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;!--&nbsp;添加外部CSS&nbsp;样式&nbsp;--&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;link&nbsp;rel="stylesheet"&nbsp;href="styles.css"&nbsp;type="text/css"&nbsp;/&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;!--&nbsp;在外部的styles.css文件中，代码如下：</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;h3&nbsp;{color:blue;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;--&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;!--&nbsp;使用javascript&nbsp;创建内部CSS&nbsp;样式&nbsp;--&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;script type="text/javascript"&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;!--</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;(function(){ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;agent&nbsp;=&nbsp;window.navigator.userAgent.toLowerCase();</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;is_op&nbsp;=&nbsp;(agent.indexOf("opera")&nbsp;!=&nbsp;-1);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;is_ie&nbsp;=&nbsp;(agent.indexOf("msie")&nbsp;!=&nbsp;-1)&nbsp;&amp;&amp;&nbsp;document.all&nbsp;&amp;&amp;&nbsp;!is_op;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;is_ch&nbsp;=&nbsp;(agent.indexOf("chrome")&nbsp;!=&nbsp;-1);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;cssStr="h3&nbsp;{color:green;}";</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;s=document.createElement("style");</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;head=document.getElementsByTagName("head").item(0);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;link=document.getElementsByTagName("link");</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;link=link.item(0);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if(is_ie)</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if(link)</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;head.insertBefore(s,link);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;else</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;head.appendChild(s);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;document.styleSheets.item(document.styleSheets.length-1).cssText=cssStr;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;else&nbsp;if(is_ch)</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;var&nbsp;t=document.createTextNode();</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;t.nodeValue=cssStr;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;s.appendChild(t);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;head.insertBefore(s,link);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;else</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{ </td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;s.innerHTML=cssStr;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;head.insertBefore(s,link);</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&nbsp;&nbsp;})();</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;//--&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;/script&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;/head&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;body&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &nbsp;&nbsp;&lt;h3&gt;在IE中我是绿色，非IE浏览器下我是蓝色！&lt;/h3&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;/body&gt;</td> 
 </tr> 
 <tr> 
 <td style="font-size:10pt; border:1px solid silver; border-collapse:collapse; padding:3px"> &lt;/html&gt;</td> 
 </tr> 
 </tbody> 
</table>

**结果**：在Firefox / Chrome / Safari / Opera 中，文字都是蓝色的。而在IE 浏览器中，文字却是绿色的。

**附加**

在IE 中添加样式内容的JavaScript 代码：

**IE 浏览器下载或者渲染的顺序可能如下：**

●   IE 下载的顺序是从上到下；

●   JavaScript 函数的执行会阻塞IE 的下载；

●   IE 渲染的顺序也是从上到下；

●   IE 的下载和渲染是同时进行的；

●   在渲染到页面的某一部分时，其上面的所有部分都已经下载完成（但并不是说所有相关联的元素都已经下载完。）

●   在下载过程中，如果遇到某一标签是嵌入文件，并且文件是具有语义解释性的（例如：JS脚本，CSS样式），那么此时IE的下载过程会启用单独连接进行下载。并且在下载后进行解析，如果JS、CSS中如有重定义，后面定义的函数将覆盖前面定义的函数。

●   解析过程中，停止页面所有往下元素的下载。样式表文件比较特殊，在其下载完成后，将和以前下载的所有样式表一起进行解析，解析完成后，将对此前所有元素（含以前已经渲染的）重新进行样式渲染。并以此方式一直渲染下去，直到整个页面渲染完成。

●   Firefox 处理下载和渲染的顺序大体相同，只是在细微之处有些差别，例如：iframe 的渲染。

[jc6_002]: http://images.cnblogs.com/cnblogs_com/xugang/WindowsLiveWriter/CSS_148B3/jc6_002_thumb.png
[jc6_002_jc6_002]: /images/20220728/ecf85f1c203f4e29971b5fdd11c34c81.png