Mermaid doesn't render when network is not available

[gyund]

Contribution guidelines

• I've read the contribution guidelines and wholeheartedly agree

I've found a bug and checked that ...

• ... the problem doesn't occur with the mkdocs or readthedocs themes
• ... the problem persists when all overrides are removed, i.e. custom_dir, extra_javascript and extra_css
• ... the documentation does not mention anything about my problem
• ... there are no open or closed issues that are related to my problem

Description

If you are writing documentation and you lose access to the internet, mermaid diagrams render as code blocks instead of the diagrams.

Expected behaviour

Mermaid diagrams are rendered

Actual behaviour

Mermaid does not display the diagram as an image when network access is unavailable.

Steps to reproduce

1. Follow these directions for setting up mermaid support: https://squidfunk.github.io/mkdocs-material/reference/diagrams/
2. Create a mermaid codeblock in a markdown file (take any example from the link above)
3. run mkdocs serve and verify the diagram is displayed
4. Disable your network adapter (or unplug your network cable)
5. Refresh the page. The diagram is now rendered as a codeblock

Package versions

• Python: Python 3.8.10
• MkDocs: mkdocs, version 1.3.0
• Material: Version: 8.2.8

Configuration

site_name: My Docs
theme: material

markdown_extensions:
  - pymdownx.superfences:
      custom_fences:
        - name: mermaid
          class: mermaid
          format: !!python/name:pymdownx.superfences.fence_code_format

System information

• Operating system: Ubuntu 20.04
• Browser: Chrome / Firefox

[squidfunk]

Thanks for reporting. Mermaid.js is loaded from a CDN, which is why local browsing still works, except for assets loaded from third-party servers. You can either provide your own Mermaid.js via extra_javascript, or use the Privacy Plugin to download all assets automatically.

Related:

• mermaid.js diagrams without JavaScript #3715
• Mermaid Diagram Offline/Privacy Path Error #3742

[gyund]

Thanks, the extra_script approach worked after downloading unpkg.com/mermaid@8.13.3/dist/mermaid.min.js from #3742 and dropping it into the folder. In case anyone else has the issue, that's the easiest way. Just update the version in the url as needed.