A tiny markdown validator. It understands GFM auto-links, and returns an exitCode of 1 if any rules are violated, making it suitable for use in CI environments. It is in use by the OpenAPI Specification, the RAML Specification and the AsyncAPI Specification, amongst others.

• Undefined internal link targets - missingAnchors[]
• Duplicated internal link targets - duplicatedAnchors[]
• Anchors containing the # character - anchorsWithHash[]
• Links with empty text - anchorsWithEmptyText[]
• Local Refs without # character - localRefNoHash[]
• Images without an alt tag - imagesWithMissingAlt[]
• yaml, json, xml or abnf examples which do not parse - nonParsingExamples[]

• Internal manually-defined anchors with no links pointing to them
• Code-blocks with no language specified - codeBlocksWithNoLanguage
• Four or more leading backticks at the beginning of a line

Options:
  -d, --debug  enable debug mode                                       [boolean]
  -s, --save   save intermediary html                                  [boolean]
  -w, --warnings  enable warnings                                      [boolean]
  -h, --help   Show help                                               [boolean]

const mdv = require('mdv');
const options = {};
const result = mdv.validate(markdownString,options);

{ imagesWithMissingAlt: 0,
  source: '../openapi-specification/versions/2.0.md',
  missingAnchors:
   [ { name: 'dataTypeType', defined: 0, seen: 1 },
     { name: 'stType', defined: 0, seen: 2 },
     { name: 'securityDefinitions', defined: 0, seen: 1 } ],
  duplicatedAnchors:
   [ { name: 'itemsMaximum', defined: 2, seen: 0, auto: false },
     { name: 'headerMaximum', defined: 2, seen: 0, auto: false } ],
  anchorsWithHash: [],
  anchorsWithEmptyText: [],
  codeBlocksWithNoLanguage: 1 }