严格的文档类型 - 表单和输入元素 [英] Strict doctype - form and input element

问题描述

有谁知道严格doctype背后的原因，不允许输入元素是表单元素的直接后代。我觉得很烦人的是，我必须包装一个提交按钮，它是另一个块级元素中的块级元素，比如说一个字段集或一个div。然而，我无法找到任何答案，为什么这实际上是。

解决方案

因此，如果您尝试直接将输入一个没有容器元素的表单，并且在xhtml 1.0 strict下验证，你会得到这样的警告：

文档类型不允许元素
输入在这里;缺少p，
h1，h2，h3，h4，h5，h6，
div，pre，address ，fieldset，
ins，delstart-tag✉
提及的元素不允许
出现在
放置它的上下文中;其他提到的
元素是唯一允许存在的
元素，并且可以包含提到的
元素。这可能意味着
您需要一个包含元素，或者
可能是您忘记了
关闭了前一个元素。

此消息的一个可能原因是
，您试图将
块级元素（例如< p>或
< table>）放入内联元素
（例如< a>，< span>或
< font>）。 b

如果你看一下表单元素的W3C定义（ http://www.w3.org/TR/html4/interact/forms.html#h-17.3 ）你可以看到元素的内容模型被定义为％块（block）。

<！ELEMENT FORM - - （％block; | SCRIPT）+
- （FORM） - 交互式表单 - >

如果您按照％block链接（ http://www.w3.org/TR/html4/sgml/dtd.html#block ），它将引导您定义为这些元素类型的元素。以下是：

 <！ENTITY％block 
P |％heading; |％list; |％预格式化| | DL | DIV | NOSCRIPT | 
 BLOCKQUOTE | FORM | HR | TABLE | FIELDSET | ADDRESS> 
  

所以，你可以看到，W3C并没有将输入或按钮定义为块级别元素。您可以搜索该页面的输入，并发现它是formctrl的内容类型：

 <！ENTITY％formctrl INPUT | SELECT | TEXTAREA | LABEL | BUTTON> 
  

实际上，输入元素默认显示为比块更多的内联块，因为他们不导致他们之前/之后的换行符。所以，不仅仅是内联元素和块级元素。因此，最终，一个表单需要直接的子元素作为块级元素，并且输入元素不符合条件。我希望能清除所有的东西。

Does anyone know the reasoning behind the strict doctype not allowing input elements to be direct descendents of a form element. I find it annoying that i have to wrap a submit button which is a block level element inside another block level element say a fieldset or a div. However, I cannot find an answer anywhere as to why this actually is.

解决方案

So if you try to put an input directly into a form without a container element, and validate under xhtml 1.0 strict, you get this warning:

document type does not allow element "input" here; missing one of "p", "h1", "h2", "h3", "h4", "h5", "h6", "div", "pre", "address", "fieldset", "ins", "del" start-tag ✉ The mentioned element is not allowed to appear in the context in which you've placed it; the other mentioned elements are the only ones that are both allowed there and can contain the element mentioned. This might mean that you need a containing element, or possibly that you've forgotten to close a previous element.

One possible cause for this message is that you have attempted to put a block-level element (such as "<p>" or "<table>") inside an inline element (such as "<a>", "<span>", or "<font>").

And if you look here at the W3C definition of a form element (http://www.w3.org/TR/html4/interact/forms.html#h-17.3) you can see that that the element's content model is defined as "%block".

<!ELEMENT FORM - - (%block;|SCRIPT)+ -(FORM) -- interactive form -->

If you follow the "%block" link (http://www.w3.org/TR/html4/sgml/dtd.html#block) that leads you to the elements that are defined as those types of elements. And those are:

<!ENTITY % block
     "P | %heading; | %list; | %preformatted; | DL | DIV | NOSCRIPT |
      BLOCKQUOTE | FORM | HR | TABLE | FIELDSET | ADDRESS">

So, as you can see, the W3C doesn't define an input or a button as a block level element. You can search that page for "input" and find that it's content type of "formctrl":

<!ENTITY % formctrl "INPUT | SELECT | TEXTAREA | LABEL | BUTTON">

And, really, input elements default display as more inline-block than block, considering they don't cause line breaks before/after them. So, there are more than just inline elements and block-level elements.

So, in the end, a form needs it's direct children to be block level elements, and input elements don't qualify. I hope that clears everything up.

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