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标准模式 HTML forbids double hyphens在评论中。
<!-- This is a perfectly valid comment - I think. -->
<!-- Invalid comment -- definitely. -->
还有三个额外的限制，以这些无效示例为例:
<!--> invalid -->
<!---> invalid -->
<!-- invalid --->
为什么要费心指定所有这些小的边缘情况？特别是，为什么禁止使用双连字符？
最佳答案
[Definition: Comments may appear anywhere in a document outside other markup; in addition, they may appear within the document type declaration at places allowed by the grammar. They are not part of the document's character data; an XML processor may, but need not, make it possible for an application to retrieve the text of comments. For compatibility, the string " -- " (double-hyphen) must not occur within comments.] Parameter entity references must not be recognized within comments.
语法不允许以--->结尾的注释
它似乎是 XML 的一个特性，只是为了确保 XML 与 SGML 保持兼容 http://www.w3.org/TR/REC-xml/#sec-comments
关于html - 为什么双连字符在 HTML 注释中无效？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/26600092/