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code-lang-shorthand

✅ Recommended 🔧 Fixable ⭐ CommonMark 🌟 GFM

🔗 Rule Source 🔗 Test Source

Enforce the use of shorthand for code block language identifiers.

Rule Details ​

The purpose of this rule is to enforce the use of shorthand language identifiers in code blocks. Some may want to use abbreviated language identifiers to keep the code blocks concise and consistent.

Using shorthand language identifiers offers several advantages: they improve readability by simplifying code, optimize file size, ensure consistency across code blocks, and make it easier for tools and automation systems to process language identifiers efficiently.

Please note that the code block language identifier detection logic is case-insensitive, so JavaScript, javascript, and JAVASCRIPT are all treated as the same language identifier.

You can find the full list of language identifiers shorthand mapping in the source code.

Examples ​

❌ Incorrect ​

Examples of incorrect code for this rule:

Default ​

md
<!-- eslint md/code-lang-shorthand: 'error' -->

```
javascript

console.log('Hello, world!');
```

```
typescript

console.log('Hello, world!');
```

```
TypeScript

console.log('Hello, world!');
```

```
TYPESCRIPT

console.log('Hello, world!');
```

```
markdown

Hello, world!
```

With override: { example: 'ex' } Option ​

md
<!-- eslint md/code-lang-shorthand: ['error', { override: { example: 'ex' } }] -->

```
example

Welcome to the example language!
```

```
Example

Welcome to the example language!
```

```
EXAMPLE

Welcome to the example language!
```

✅ Correct ​

Examples of correct code for this rule:

Default ​

md
<!-- eslint md/code-lang-shorthand: 'error' -->

    Indented code block

```
Fenced code block without lang
```

```js
console.log('Hello, world!');
```

```ts
console.log('Hello, world!');
```

```md
Hello, world!
```

With allow: ['javascript', 'typescript'] Option ​

md
<!-- eslint md/code-lang-shorthand: ['error', { allow: ['javascript', 'typescript'] }] -->

```javascript
console.log('Hello, world!');
```

```typescript
console.log('Hello, world!');
```

Options ​

js
'md/code-lang-shorthand': ['error', {
  allow: [],
  override: {},
}]

allow ​

Type: string[] / Default: []

An array of code block language identifiers to allow. Each value must be the full, unabridged language identifier.

The values in this array are case-insensitive, since each value is normalized to lowercase when compared with the code block's language identifier.

Allowing specific language identifiers ​

For example, to allow the javascript and typescript language identifiers:

js
'md/code-lang-shorthand': ['error', {
  allow: ['javascript', 'typescript'],
}]

Allowing overridden language identifiers ​

For example, to allow an overridden example language identifier:

js
'md/code-lang-shorthand': ['error', {
  allow: ['example'],
  override: {
    example: 'ex',
  },
}]

override ​

Type: Record<string, string> / Default: {}

An object where the key is the full, unabridged language identifier and the value is the abbreviated form. Both keys and values are treated case-insensitively and normalized to lowercase, so override: { EXAMPLE: 'EX' } is equivalent to override: { example: 'ex' } and will produce the abbreviation ex.

Adding a new abbreviation ​

For example, to shorten the example language identifier to ex:

js
'md/code-lang-shorthand': ['error', {
  override: {
    example: 'ex',
  },
}]

Overriding an existing abbreviation ​

For example, to change the default abbreviation for javascript to mjs:

js
'md/code-lang-shorthand': ['error', {
  override: {
    javascript: 'mjs',
  },
}]

Fix ​

This rule converts unabridged code block language identifiers into their abbreviated forms.