remark-lint-fenced-code-flag-case

remark-lint-fenced-code-flag-case

This is a remark-lint rule to warn when fenced code blocks have inconsistent or improperly cased language flags. Also comes with full unicode support.

This check is useful when using a tool like prettier that formats fenced code blocks, since such tools do not consistently recognize uppercase or mixed-case code flags. That is: code fenced with the flag typescript or markdown will be formatted while code fenced with the flag TypeScript or MARKDOWN may be silently ignored, even as syntax highlighting still works, which results in a false sense of correctness.

---

• Install
• Usage
  • Via API
  • Via remark-cli
  • Via unified configuration
• API
  • Options
• Examples
  • ok-missing.md
  • ok-lower.md
  • not-ok-mixed.md
  • not-ok-upper.md
• Related
• Contributing and Support
  • Contributors

Install

Due to the nature of the unified ecosystem, this package is ESM only and cannot be require'd.

npm install --save-dev remark-lint-fenced-code-flag-case

Usage

Via API

import { read } from 'to-vfile';
import { reporter } from 'vfile-reporter';
import { remark } from 'remark';
import remarkLint from 'remark-lint';
import lintFencedCodeFlagCase from 'remark-lint-fenced-code-flag-case';

const file = await remark()
  .use(remarkLint)
  .use(lintFencedCodeFlagCase)
  .process(await read('example.md'));

console.log(reporter(file));

Via remark-cli

remark --use remark-lint --use lint-fenced-code-flag-case README.md

Via unified configuration

In package.json:

  /* … */
  "remarkConfig": {
    "plugins": [
      "remark-lint-fenced-code-flag-case"
      /* … */
    ]
  },
  /* … */

In .remarkrc.js:

module.exports = {
  plugins: [
    // …
    'lint-fenced-code-flag-case'
  ]
};

In .remarkrc.mjs:

import lintFencedCodeFlagCase from 'remark-lint-fenced-code-flag-case';

export default {
  plugins: [
    // …
    lintFencedCodeFlagCase
  ]
};

API

Detailed interface information can be found under docs/.

Options

This rule supports standard configuration that all remark lint rules accept (such as false to turn it off or [1, options] to configure it).

Additionally, this plugin recognizes the following options:

case

Valid values: "lower" | "upper" | "capitalize"
Default: "lower"

All code fence flags must be of the specified case. Code fences without flags are ignored.

Examples

ok-missing.md

In

# Document

```
Text.
```

Out

No messages.

ok-lower.md

In

# Document

```js
const str = 'string';
```

```javascript
const str = 'string';
```

Out

No messages.

not-ok-mixed.md

In

# Document

```Js
const str = 'string';
```

```JavaScript
const str = 'string';
```

Out

3:1-5:4: Code fence flag "Js" should be "js"
7:1-10:5: Code fence flag "JavaScript" should be "javascript"

not-ok-upper.md

In

# Document

```JS
const str = 'string';
```

```JAVASCRIPT
const str = 'string';
```

Out

3:1-5:4: Code fence flag "JS" should be "js"
7:1-10:5: Code fence flag "JAVASCRIPT" should be "javascript"

Related

• remark-lint-fenced-code-flag — warn when fenced code blocks occur without language flag.
• remark-lint-fenced-code-marker — warn when fenced code markers violate the given style.

Contributing and Support

New issues and pull requests are always welcome and greatly appreciated! 🤩 Just as well, you can star 🌟 this project to let me know you found it useful! ✊🏿 Thank you!

See CONTRIBUTING.md and SUPPORT.md for more information.

Contributors

See the table of contributors.