# mdv

[![Build status](https://travis-ci.org/Mermade/mdv.svg?branch=master)](https://travis-ci.org/Mermade/mdv)

A tiny markdown validator. It understands [GFM auto-links](https://gist.github.com/asabaylus/3071099), 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](https://github.com/OAI/OpenAPI-Specification), the [RAML Specification](https://github.com/raml-org/raml-spec) and the [AsyncAPI Specification](https://github.com/asyncapi/asyncapi), amongst others.

## Errors

* 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[]`

## Warnings

* 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

## Usage

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

### API

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

### Example output

```javascript
{ 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 }
```