Mermaid: document mmdc attribute

[ahus1]

Thanks for providing release 2.0.5 of this library!

I've tested the Mermaid functionality in release 2.0.5 and after some trial-and error I found out what to put into mmdc. Apparently I needed to put in the JavaScript file of the CLI in there, as it is passed to the node executable directly.

First I tried to pass in the CLI executable (the mmdc.cmd on Windows), but then Node complained that it couldn't parse a CMD file. After looking at the source code I figured out that passing on the JavaScript file mentioned in the mmdc.cmd would probably be the thing to do.

You find my setup in this issue's comment: https://github.com/asciidoctor/asciidoctor-intellij-plugin/issues/534#issuecomment-703832304

I wonder:

• did I use mmdc attribute correctly?
• should there be some additional documentation making it easier for users to "do the right thing"®?

[pepijnve]

You're right, that isn't really obvious anymore. Combined with the error stating you should set the mermaid attribute the situation is definitely less than ideal.

To be honest I only really develop/test on macos, windows is a bit under tested. On UNIX-like systems the mmdc attribute can still point to the binary wrapper since that's just a JS file as well that starts with #!/usr/bin/env node. I had not considered the windows .cmd case. I'll see what I can do about this.

[ahus1]

I am happy that there is the new release with the greatly improved mermaid support. Adding this small workaround on Windows is fine for me.

[pepijnve]

The tricky thing is that in order to make the node process terminate on error I have to inject the --unhandled-rejections=strict node parameter somehow (see #257 for the details). I could detect a .cmd file, try to parse/scrape it using a regex to figure out where the main script is located and then launch node. That would make things 'just work' but it feels a bit brittle since the slightest change in the batch scripts node generates might end up breaking the mermaid integration on Windows again.

[mojavelinux]

I'm pretty sure you can pass additional flags to the node invocation using the NODE_OPTIONS environment variable. See https://nodejs.org/api/cli.html#cli_node_options_options

[pepijnve]

I'm pretty sure you can pass additional flags to the node invocation using the NODE_OPTIONS environment variable.

That is a much, much better solution than what I came up with. Thanks Dan! I see a 2.0.6 release in our near future 😄

[ahus1]

@pepijnve - I see that you opened issue https://github.com/mermaidjs/mermaid.cli/issues/77 with mermaid. As mermaid moved to a new GitHub repo:

• maybe this has already been handled here in the new repo: https://github.com/mermaid-js/mermaid-cli/pull/19
• if this is not the case, and if the problem persists, may I suggest to close the old issue and open a new issue in https://github.com/mermaid-js/mermaid-cli?

[pepijnve]

Yep, the PR fixes the underlying root cause. That #77 issue is still relevant for the old version though, so it might be best to just leave the issue in place. I left a comment on issue #77 pointing to the PR, the maintainers can close the issue if they like. No idea why the mermaid developers made such a mess of their repos though; it's needlessly confusing for everyone.