How to tell if loaded page is true XML-processed XHTML or not, using devtools or JavaScript snippet

61 Views Asked by myf At 15 September 2023 at 10:25

Inspecting Firefox system page that is displayed when connection to remote server fails shows clear signs it is a true application/xhtml+xml page:

There is explicit xmlns="http://www.w3.org/1999/xhtml", all elements, even void ones, have closing tags, so it most probably is processed as XML. This brings the question:

What would be the easiest way for script loaded in such page or for Developer Tools command to tell XML processed page apart from regular HTML?

Checking document.documentElement.namespaceURI property gives "http://www.w3.org/1999/xhtml" in both cases.

What DOM property or method could serve as sign page is XML?
Or is some more complex detection procedure necessary (like doing some DOM/XSLT/entities stuff that works exclusively in XML) to be sure?

Source of the depicted system page is presumably view-source:chrome://global/content/aboutNetError.xhtml but, it does not work when displayed directly.

Original Q&A

There are 1 best solutions below

Martin Honnen On 15 September 2023 at 11:58 BEST ANSWER

document.contentType should give you "application/xhtml+xml" for XML parsed XHTML documents and "text/html" for HTML(5) parsed HTML documents.

Specs: WHATWG:contentType, docs: MDN: Document: contentType property.

Demo:

This document's <code>contentType</code>:<br/>
<script>document.body.append(document.contentType)</script>

<hr>

<p>Iframe with minimal XHTML and same content:</p>

<iframe src='data:application/xhtml+xml,
  <html xmlns="http://www.w3.org/1999/xhtml"><body>
  This document%27s <code>contentType</code>:<br/>
  <script>document.body.append(document.contentType) </script>
  </body></html>
'></iframe>

How to tell if loaded page is true XML-processed XHTML or not, using devtools or JavaScript snippet

There are 1 best solutions below

Related Questions in JAVASCRIPT

Related Questions in HTML

Related Questions in XML

Related Questions in XHTML

Related Questions in DETECTION

Trending Questions

Popular # Hahtags

Popular Questions