Lint all JavaScript in markdown files by default

[feross]

ESLint supports the notion of "processors" which allows us to extract JS from markdown files and lint it to ensure it is in standard style. https://eslint.org/docs/user-guide/configuring#specifying-processor

That would let us eliminate this whole section of the readme which describes how to install eslint-plugin-markdown, run standard with the --plugin flag. In the end you need to actually run standard twice if you do this: standard && standard --plugin markdown '**/*.md'

I think we can do better. Let's just do the right thing out of the box.

We should probably do the same for <script> tags in HTML files too, while we're at it.

We can provide a --no-md or --no-html escape hatch for those who need it. But ideally, this just does the right thing 99.9% of the time.

Thoughts?

[mightyiam]

Brilliant. I'd love that. Would probably break some projects.

Would that be supported merely by extending from eslint-config-standard or would it require the executable? I would prefer the former, if possible.

[feross]

We'd put it directly in eslint-config-standard.

[vweevers]

We should probably do the same for <script> tags in HTML files too, while we're at it.

One requirement for this is that generated HTML (like a code coverage report) is excluded. Such HTML is typically git-ignored though, which tells standard to ignore it too, so it's probably fine.

[vweevers]

I've seen and written code examples in READMEs that are not 100% correct, for example to quickly demonstrate two ways to achieve the same thing:

const x = doItOneWay()

// Alternatively:
const x = doItAnotherWay()

I guess standard would implicitly impose a rule to split such snippets? In this case, to not reassign x.

[feross]

@vweevers Yeah, we'd certainly need to disable some of the rules for examples, like unused variables for example. I think we can look at what standard-markdown disables as a starting point: https://github.com/zeke/standard-markdown/blob/2f044f48eed5f7162147e7927b65a61387200341/lib/linter.js#L8-L15

[feross]

I attempted to get this working for standard 16 but ran into issues. Help would be appreciated to figure it out!

Here's what I tried:

eslint-config-standard

1. Install eslint-plugin-markdown as a peer dep of eslint-config-standard (2.0.0-rc.0 was latest at the time)
2. Add "extends": ["plugin:markdown/recommended"] to the eslint.json file.

standard

1. Install eslint-plugin-markdown as a dep of eslint-config-standard
2. Add extensions: ['.md'] to eslintConfig in options.js:

observed behavior

  /Users/feross/code/standard/CHANGELOG.md:654:10: 'foo' is defined but never used. (no-unused-vars)

Rules like no-unused-vars are being enforced, which should be ignored for markdown files. From the docs for eslint-plugin-markdown:

Some rules that catch mistakes in regular code are less helpful in documentation. For example, no-undef would flag variables that are declared outside of a code snippet because they aren't relevant to the example. The plugin:markdown/recommended config disables these rules in Markdown files:

https://github.com/eslint/eslint-plugin-markdown#frequently-disabled-rules

Help appreciated!

[jimmywarting]

bump. would like to see this land