角度括号是否需要在嵌套样式元素中进行HTML转义? [英] Do Angle Brackets Need to be HTML-Escaped in Nested Style Elements?
问题描述
假设您在HTML文档中有以下内容:
< style>
ul.foo> li {
/ * etc * /
}
< / style>
是否有效的HTML语法 - 将大于孩子的选择符作为 $ gt;
?
< style>
ul.foo& gt; li {
/ * etc * /
}
< / style>
我明白这是不必要的,但它是好的形式吗?
HTML,但不是有效的CSS,因为嵌入的样式表根本不会被解析为HTML;它被解析为CSS,这意味着& gt;
可以从字面上看出来。 & gt;
不是有效的选择器,因此它不是有效的CSS。 HTML;在XHTML中, 有效,浏览器将将& gt;
解码为> ;
在将样式表解析为CSS之前。以下数据URI演示了这一点:
data:application / xhtml + xml,< html xmlns = http://www.w3.org/1999/xhtml >< HEAD><风格> ul.foo&安培; GT;李{颜色:红色}< /风格>< /头>< body>< ul class =foo>< li> Foo< / li>< / ul>< / body>< / html>
然而,就像在HTML中一样,在这个特定的上下文中没有必要,因为在您链接到的问题,但它仍被认为是格式良好的XHTML。但通常情况下,将嵌入式脚本和样式表放入CDATA部分比编码每个<
,>
和&
:
< style>
/ *<![CDATA [* /
ul.foo> li {
/ * etc * /
}
/ *]]> * /
< / style>
Suppose you have the following in your HTML document:
<style>
ul.foo > li {
/* etc */
}
</style>
Is it valid syntax to HTML-escape the greater-than child selector as $gt;
?
<style>
ul.foo > li {
/* etc */
}
</style>
I understand it's not necessary, but is it good form?
It's valid HTML, but not valid CSS, because the embedded stylesheet isn't parsed as HTML at all; it's parsed as CSS, meaning that the >
is seen literally. >
is not a valid selector, and therefore it's not valid CSS.
This is only true of HTML; in XHTML, it is valid and browsers will decode the >
into >
before parsing the stylesheet as CSS. The following data URI demonstrates this:
data:application/xhtml+xml,<html xmlns="http://www.w3.org/1999/xhtml"><head><style>ul.foo>li{color:red}</style></head><body><ul class="foo"><li>Foo</li></ul></body></html>
Just like in HTML, though, it's not necessary in this specific context, for the reason given in the question you link to, but it's still considered well-formed XHTML. But generally, putting embedded scripts and stylesheets into CDATA sections is preferred over encoding every single <
, >
and &
:
<style>
/* <![CDATA[ */
ul.foo > li {
/* etc */
}
/* ]]> */
</style>
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