README.md

markdownlint-rule-helpers

A collection of markdownlint helper functions for custom rules

Overview

The Markdown linter markdownlint offers a variety of built-in validation rules and supports the creation of custom rules. The internal rules share various helper functions; this package exposes those for reuse by custom rules.

API

Undocumented - This package exports the internal functions as-is. The APIs were not originally meant to be public, are not officially supported, and may change from release to release. There are brief descriptive comments above each function, but no JSDoc annotations. That said, some of what's here will be useful to custom rule authors and may avoid duplicating code.

Examples

Using Helpers from a Custom Rule

const { forEachLine, getLineMetadata } = require("markdownlint-rule-helpers");

/** @type import("markdownlint").Rule */
module.exports = {
  "names": [ "every-n-lines" ],
  "description": "Rule that reports an error every N lines",
  "tags": [ "test" ],
  "parser": "none",
  "function": (params, onError) => {
    const n = params.config.n || 2;
    forEachLine(getLineMetadata(params), (line, lineIndex) => {
      const lineNumber = lineIndex + 1;
      if ((lineNumber % n) === 0) {
        onError({
          "lineNumber": lineNumber,
          "detail": "Line number " + lineNumber
        });
      }
    });
  }
};

Applying Recommended Fixes

const { "sync": markdownlintSync } = require("markdownlint");
const markdownlintRuleHelpers = require("markdownlint-rule-helpers");

function fixMarkdownlintViolations(content) {
  const fixResults = markdownlintSync({ strings: { content } });
  return markdownlintRuleHelpers.applyFixes(content, fixResults.content);
}

See also: markdownlint built-in rule implementations.

Tests

None - The entire body of code is tested to 100% coverage by the core markdownlint project, so there are no additional tests here.