Question

53

Get DocType of an HTML as string with Javascript

rated 0 times [ 55] [ 2] / answers: 1 / hits: 24048 / 13 Years ago, sun, may 22, 2011, 12:00:00

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.

Is there a way to get the doctype string in all browsers as in chrome and safari?

Thanks!

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josh

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answered 13 Years ago claudia · Accepted Answer

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 + '' : '')

         + '>';

This method returns the correct string for valid (HTML5) doctypes, eg:

<!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>

Explanation of the code:

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