`extra_*` settings do not support pointing to CDNs

[Frederick-S]

This error occurs when I run mkdocs serve command. And the output shows:

INFO    -  Building documentation...
INFO    -  Cleaning site directory

Bad path: https:\\cdnjs.cloudflare.com\ajax\libs\mathjax\2.7.1\mathjax.js?config=tex-ams-mml_htmlormml

The output shows mkdocs converts url to lower case, but mathjax cdn is case sensitive, so the converted url is not valid.

Here is my extra_javascript setting: extra_javascript: ['https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML', 'mathjaxconfig.js'].

And additional information:

OS: Windows 10
Python: 3.6.1
mkdocs: 0.17.0

[waylan]

I believe that the extra_javascript setting assumes that all provided paths are for local files in your docs_dir. You are getting the "bad path" error because the provided string is not a valid path to a local file.

There is currently no support for listing external resources in the extra_* settings. And its not clear to me if there should be. I'm considering this as a feature request.

As a workaround, you would need to host the MathJax lib locally (include a copy in the docs_dir) or use a theme custom_dir to include the remote MathJax lib in the libs block of the template (as described here).

[facelessuser]

I'm pretty sure this used to work and was broken at some point. I'm not sure why this would be specific disallowed and required to be a local file. This just doesn't seem practical to how people are actually found to try and use this and would expect this to work.

[waylan]

I'm pretty sure this used to work and was broken at some point.

Did it? I'm not sure one way or the other. I just know it doesn't work now. If it did work, then that is a regression and this should be a bug.

[facelessuser]

I, at one point, used to do exactly what is described in this issue to apply MathJax. I do things a bit differently now as I have reasons to do so, but due to how I used it in the past, I would try to do this in the future if I needed to pull in a library from a CDN.

So I don't know when it broke, but I would have thought this breakage a bug.

[waylan]

It appears that this line (list(os.path.normcase(path) for path in value)) was introduced in #1308. In fact, I expect that is where the "bad path" error is coming from. This is definitely a regression and a bug.

[facelessuser]

My personal opinion on MathJax is that it is a weighty library to include on every page even if it doesn't use math. So I personally shy away from including via extra.

I prefer to append the library to the end of that file I am including math in: https://raw.githubusercontent.com/facelessuser/pymdown-extensions/master/docs/src/markdown/_snippets/mathjax.md. So I create a markdown partial that I include at the bottom of other markdown pages with a Markdown extension.

You can just copy something similar at the body of the pages that have math, or use a Markdown extension like this (which I am the author of) or I assume this (which uses a less whimsical syntax if that is something that bothers you). Also you could probably accomplish this by customizing your theme with a template override, or even use the new MkDocs plugin system.

But either way, it will be nice to have this issue fixed.

[waylan]

I just remembered why that change was made. In post_validation we are issuing a warning for any CSS/JavaScript files which are not listed as we transition the behavior to not autofill. However, to do a "contains" check, the paths need to be normalized as the comparison is a dumb string comparison, not a comparison of (url or path) objects.

I wonder if this would suffice, or if we need something more sophisticated:

list(os.path.normcase(path) for path in value if not path.startswith('http'))

As a reminder, in the next major release, this entire thing will be removed and the the extra settings will simply be validated as being a list.

[facelessuser]

I think if it passes through URLs, people will be fine with it. People just want their CDN links to work 🙂 .