为什么开发人员在JavaScript中分离<脚本？ [英] Why Do Developers Split Up <script in JavaScript?

问题描述

我看到很多这样的东西：
S =< scr+ipt language = \JavaScript1.2 \> \\\
<！ - -\\\
;

为什么他们这样做，是否存在一个应用程序/浏览器，如果您直接使用< script>？

解决方案

Javascript外部脚本加载陌生性

取自 bobince的回答：

要查看问题，请查看其脚本元素中的顶部
行：

 < script type =text / javascript> 
 document.write（'< script src =set1.aspx？v = 1234
 type =text / javascript>< / script>'）; 
< / script> 
  

所以一个HTML解析器出现，看到
开始< script>标记。在
< script>内，正常< tag>解析
被禁用（以SGML术语，
元素具有CDATA内容）。要在脚本块结束处查找
，HTML
解析器将查找匹配的
close-tag< / script>。

它发现的第一个是字符串文本中的
。 HTML
解析器无法知道它在
字符串文字中，因为HTML解析器
不知道JavaScript
语法的任何内容，它们只知道CDATA。所以
你实际上说的是：

 < script type =text / javascript> 
 document.write（'< script src =set1.aspx？v = 1234
 type =text / javascript> 
< / script> 
  

也就是说，一个未结束的字符串文字
和一个未完成的函数调用，这些
导致JavaScript错误而
所需的脚本标记从不写入。

解决问题的常见尝试是
：

  document.write（'...< / scr'+'ipt>'）; 
  

这并不能解释为什么它会在开始标记中完成。

I see so many things like this: S = "<scr" + "ipt language=\"JavaScript1.2\">\n<!--\n";

Why do they do this, is there an application/browser that messes up if you just use straight "<script>"?

解决方案

Have a look at this question:

Javascript external script loading strangeness.

Taken from bobince's answer:

To see the problem, look at that top line in its script element:

<script type="text/javascript">
    document.write('<script src="set1.aspx?v=1234"
                           type="text/javascript"></script>');
</script>

So an HTML parser comes along and sees the opening <script> tag. Inside <script>, normal <tag> parsing is disabled (in SGML terms, the element has CDATA content). To find where the script block ends, the HTML parser looks for the matching close-tag </script>.

The first one it finds is the one inside the string literal. An HTML parser can't know that it's inside a string literal, because HTML parsers don't know anything about JavaScript syntax, they only know about CDATA. So what you are actually saying is:

<script type="text/javascript">
    document.write('<script src="set1.aspx?v=1234"
                           type="text/javascript">
</script>

That is, an unclosed string literal and an unfinished function call. These result in JavaScript errors and the desired script tag is never written.

A common attempt to solve the problem is:

document.write('...</scr' + 'ipt>');

This wouldn't explain why it's done in the start tag though.

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