HTML 5 是否需要`<html xmlns="http://www.w3.org/1999/xhtml">`
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Does HTML 5 need `<html xmlns="http://www.w3.org/1999/xhtml">`
提问by user1830984
When writing a html 5 doctype, do you suppose to include the <html xmlns="http://www.w3.org/1999/xhtml">as you did when previously using HTML4 doctype or should a different xhtml be used?
在编写 html 5 doctype 时，您<html xmlns="http://www.w3.org/1999/xhtml">是否想像以前使用 HTML4 doctype 时那样包含 ，还是应该使用不同的 xhtml？
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
采纳答案by mohammad mohsenipur
No, you don't need to include it. This should be enough.
不，您不需要包含它。这应该足够了。
<!doctype html>
<html>
回答by BoltClock
HTML5 does not require the use of the xmlnsattribute as that is specific to XHTML (which means not even HTML 4 uses it either).
HTML5 不需要使用该xmlns属性，因为它是 XHTML 特有的（这意味着即使 HTML 4 也不使用它）。
If you're just serving regular HTML5, then you can leave out that attribute entirely:
如果您只是提供常规 HTML5，那么您可以完全省略该属性：
<!DOCTYPE html>
<html>
The xmlnsattribute is only required if you're writing and serving XML-serialized HTML5, aka XHTML5.
xmlns仅当您编写和提供 XML 序列化的 HTML5，即 XHTML5 时，才需要该属性。
回答by SDC
No you don't. In fact, if you include it, then it isn't HTML5, it's xhtml.
不，你没有。实际上，如果包含它，那么它就不是 HTML5，而是 xhtml。
The xmlnspart is an XML namespace reference. HTML5 is not XML.
该xmlns部分是一个 XML 命名空间引用。HTML5 不是 XML。
In fact, if you were using that xmlnspreviously, then you weren't using HTML4 either, you were using xhtml. They're not the same.
事实上，如果您以前使用xmlns过它，那么您也不是在使用 HTML4，而是在使用 xhtml。他们不一样。
