eslint-plugin-mark

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en-capitalization

🔧 Fixable ⭐ CommonMark 🌟 GFM

🔗 Rule Source 🔗 Test Source

Enforce the use of capital letters at the beginning of sentences.

Rule Details ​

This rule enforces the use of capital letters at the beginning of sentences in Markdown documents. Maintaining consistent capitalization improves document readability and professionalism.

The rule checks the first letter of text content in paragraphs and headings (depending on configuration) to ensure proper capitalization of sentences. When a sentence begins with a lowercase letter, the rule flags it as a violation and can automatically fix the issue by converting the first letter to uppercase.

Examples ​

❌ Incorrect ​

Examples of incorrect code for this rule:

md
this sentence starts with a lowercase letter.

a paragraph with multiple sentences. only the first one is checked.

✅ Correct ​

Examples of correct code for this rule:

md
This sentence starts with a capital letter.

A paragraph with multiple sentences. This one correctly starts with uppercase.

## this heading is not checked by default due to skipHeading option

Options ​

js
'mark/en-capitalization': ['error', {
  skipHeading: true,
  skipListItem: true,
}]

skipHeading ​

Default: true

When set to true, headings are not checked for capitalization. This is useful for documentation styles that intentionally use lowercase headings or for code-like headings.

skipListItem ​

Default: true

When set to true, paragraphs in list items are not checked for capitalization. This is helpful for lists that might contain sentence fragments or code examples.

When Not To Use It ​

You might want to disable this rule if:

  • You're working with a documentation style guide that permits or requires lowercase at the beginning of sentences
  • Your document contains many code examples or technical terms that conventionally start with lowercase
  • You're writing in a language other than English or a language that doesn't follow the same capitalization rules

AST ​

This rule examines the AST for Paragraph and Heading nodes, finds their first text node, and checks if it starts with a lowercase letter.