为什么 <plaintext> 之后的任何东西都显示为已编码？

Question

为什么在 <plaintext> 之后的这段代码中，所有的东西都被编码了？甚至 </plaintext> 或 </body>:

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <p>The markup for this is 01</p>
    <plaintext>
        <h1>Main heading goes here</h1>
        <p>First paragraph goes here</p>
        <h2>Sub-heading goes here</h2>
    </plaintext>
    <p>The markup for this is 02</p>
    <h2>test 01</h2>
    <h2>test 02</h2>
</body>
</html>

jsfiddle

Answer 1

因为那是 <plaintext> does:

The HTML Plaintext Element () renders everything following the start tag as raw text, without interpreting any HTML. There is no closing tag, since everything after it is considered raw text.

Note: Do not use this element. This element has been deprecated since HTML 2 and was never implemented by all browsers; even those that did implement it didn't do so consistently. In addition, it is obsoleted in HTML 5; browsers that still accept it may simply treat it as a <pre> element, which still interprets HTML within, even though that's not what you probably want.

（我的重点）

<plaintext> 喝了你的 HTML 奶昔，之后的一切都不再 HTML.

<plaintext> 对任何 HTML 文档来说都是一个打击；更重要的是，它在 XHTML 文档中毫无意义（要求每个标签都正确嵌套和关闭）。

<plaintext> 只有一种可能的用途：在任何纯文本文档上方粘贴 HTML header，而无需检查和调整该文档的内容。

有趣的事实

<plaintext> 出现在 Tim Berners-Lee 于 1992 年分发的第一个 HTML 代码列表中。请注意最后一段。

Plaintext

This tag indicates that all following text is to be taken litterally, up to the end of the file. Plain text is designed to be represented in the same way as example XMP text, with fixed width character and significant line breaks. Format:

<PLAINTEXT>

This tag allows the rest of a file to be read efficiently without parsing. Its presence is an optimisation. There is no closing tag.

（来源：http://www.w3.org/History/19921103-hypertext/hypertext/WWW/MarkUp/Tags.html）

为什么 <plaintext> 之后的任何东西都显示为已编码？

Why any thing after <plaintext> is shown as encoded?

html

plaintext

有趣的事实