使用Javascript将HTML的DocType作为字符串 [英] Get DocType of an HTML as string with Javascript
问题描述
我知道我可以通过 document.doctype 或 document.childNodes [0] 访问doctype对象我的问题是将doctype作为一个字符串。我可以通过调用 document.doctype 返回<！DOCTYPE html PUBLIC - // W3C // DTD HTML 4.01 // ENhttp://www.w3.org/TR/html4/strict.dtd> 。但是在Firefox中，调用 document.doctype 返回DocumentType对象。
I know that I can access to doctype object via document.doctype or document.childNodes[0] but my problem is getting doctype as a string. I can do this in chrome and safari by calling document.doctype which returns <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">. However in Firefox, calling document.doctype returns DocumentType object.
有没有办法在chrome和safari中获得所有浏览器中的doctype字符串？
Is there a way to get the the doctype string in all browsers as in chrome and safari?
谢谢
推荐答案
在所有兼容的浏览器（包括Chrome / Safari）中， document.doctype 还返回一个 对象，请访问w3.org/TR/DOM-Level-3-Core/core.html#ID-412266927rel =noreferrer> 以下代码可用于生成有效的DOCTYPE字符串。
In all compliant browsers (including Chrome/Safari), document.doctype also returns a DocumentType object. The following code can be used to generate a valid DOCTYPE string.
var node = document.doctype;
var html = "<!DOCTYPE "
+ node.name
+ (node.publicId ? ' PUBLIC "' + node.publicId + '"' : '')
+ (!node.publicId && node.systemId ? ' SYSTEM' : '')
+ (node.systemId ? ' "' + node.systemId + '"' : '')
+ '>';
此方法返回正确的字符串 valid（HTML5）doctypes ，例如：
This method returns the correct string for valid (HTML5) doctypes, eg:
-
<！DOCTYPE html> -
<！DOCTYPE html SYSTEMabout：legacy-compat> code> -
<！DOCTYPE HTML PUBLIC - // W3C // DTD HTML 4.0 // ENhttp：//www.w3 .org / TR / REC-html40 / strict.dtd>
<!DOCTYPE html><!DOCTYPE html SYSTEM "about:legacy-compat"><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">
代码说明：
node.name # Holds the name of the root element, eg: HTML / html
node.publicId # If this property is present, then it's a public document type.
#>Prefix PUBLIC
!node.publicId && node.systemId
# If there's no publicId, but a systemId, prefix SYSTEM
node.systemId # Append this if present
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