remark-validate-links
remark plugin to check that markdown links and images point to existing local files and headings in a Git repo.
For example, this document does not have a heading named Hello
.
So if weโd link to it ([welcome](#hello)
), weโd get a warning.
Links to headings in other markdown documents (examples/foo.md#hello
) and
links to files (license
or index.js
) are also checked.
Contents
- What is this?
- When should I use this?
- Install
- Use
- API
- Examples
- Integration
- Types
- Compatibility
- Security
- Related
- Contribute
- License
What is this?
This package is a unified (remark) plugin to check local links in a Git repo.
unified is a project that transforms content with abstract syntax trees (ASTs). remark adds support for markdown to unified. mdast is the markdown AST that remark uses. This is a remark plugin that inspects mdast.
When should I use this?
This project is useful if you have a Git repo, such as this one, with docs in
markdown and links to headings and other files, and want to check whether
theyโre correct.
Compared to other links checkers, this project can work offline (making it fast
en prone to fewer false positives), and is specifically made for local links in
Git repos.
This plugin does not check external URLs (see
remark-lint-no-dead-urls
) or undefined references
(see remark-lint-no-undefined-references
).
Install
This package is ESM only. In Node.js (version 14.14+, or 16.0+), install with npm:
npm install remark-validate-links
In Deno with esm.sh
:
import remarkValidateLinks from 'https://esm.sh/remark-validate-links@11'
In browsers with esm.sh
:
<script type="module">
import remarkValidateLinks from 'https://esm.sh/remark-validate-links@11?bundle'
</script>
Use
Say we have the following file, example.md
:
# Alpha
Links are checked:
This [exists](#alpha).
This [one does not](#does-not).
# Bravo
Headings in `readme.md` are [checked](readme.md#no-such-heading).
And [missing files are reported](missing-example.js).
Definitions are also checked:
[alpha]: #alpha
[charlie]: #charlie
References w/o definitions are not checked: [delta]
And a module, example.js
:
import {read} from 'to-vfile'
import {remark} from 'remark'
import remarkValidateLinks from 'remark-validate-links'
main()
async function main() {
const file = await remark()
.use(remarkValidateLinks)
.process(await read('example.md'))
console.log(reporter(file))
}
Now, running node example
yields:
example.md
6:6-6:31 warning Link to unknown heading: `does-not` missing-heading remark-validate-links
11:5-11:53 warning Link to unknown file: `missing-example.js` missing-file remark-validate-links
16:1-16:20 warning Link to unknown heading: `charlie` missing-heading remark-validate-links
โ 3 warnings
(Note that readme.md#no-such-heading
is not warned about, because the API does
not check headings in other Markdown files).
API
This package exports no identifiers.
The default export is remarkValidateLinks
.
unified().use(remarkValidateLinks[, options])
Check that markdown links and images point to existing local files and headings in a Git repo.
โ ๏ธ Important: The API in Node.js checks links to headings and files but does not check whether headings in other files exist. The API in browsers only checks links to headings in the same file. The CLI can check everything.
options
Typically, you donโt need to configure remark-validate-links
, as it detects
local Git repositories.
options.repository
URL to hosted Git (string?
or false
).
If repository
is nullish, the Git origin remote is detected.
If the repository resolves to something npm understands as
a Git host such as GitHub, GitLab, or Bitbucket, then full URLs to that host
(say, https://github.com/remarkjs/remark-validate-links/readme.md#install
) can
also be checked.
If youโre not in a Git repository, you must pass repository: false
explicitly.
options.root
A root
(string?
) can also be passed, referencing the local Git root
directory (the folder that contains .git
).
If both root
and repository
are nullish, the Git root is detected.
If root
is not given but repository
is, file.cwd
is used.
options.urlConfig
If your project is hosted on github.com
, gitlab.com
, or bitbucket.org
,
this plugin can automatically detect the url configuration.
Otherwise, use urlConfig
to specify this manually.
For this repository (remarkjs/remark-validate-links
on GitHub) urlConfig
looks as follows:
{
// Domain of URLs:
hostname: 'github.com',
// Path prefix before files:
prefix: '/remarkjs/remark-validate-links/blob/',
// Prefix of headings:
headingPrefix: '#',
// Hash to top of markdown documents:
topAnchor: '#readme',
// Whether lines in files can be linked:
lines: true
}
If this project were hosted on Bitbucket, it would be:
{
hostname: 'bitbucket.org',
prefix: '/remarkjs/remark-validate-links/src/',
headingPrefix: '#markdown-header-',
lines: false
}
Examples
Example: CLI
Itโs recommended to use remark-validate-links
on the CLI with
remark-cli
.
Install both with npm:
npm install remark-cli remark-validate-links --save-dev
Letโs say we have a readme.md
(this current document) and an example.md
with the following text:
# Hello
Read more [whoops, this does not exist](#world).
This doesnโt exist either [whoops!](readme.md#foo).
But this does exist: [license](license).
So does this: [readme](readme.md#install).
Now, running ./node_modules/.bin/remark --use remark-validate-links .
yields:
example.md
3:11-3:48 warning Link to unknown heading: `world` missing-heading remark-validate-links
5:27-5:51 warning Link to unknown heading in `readme.md`: `foo` missing-heading-in-file remark-validate-links
readme.md: no issues found
โ 2 warnings
Example: CLI in npm scripts
You can use remark-validate-links
and remark-cli
in an npm script to
check and format markdown in your project.
Install both with npm:
npm install remark-cli remark-validate-links --save-dev
Then, add a format script and configuration to package.json
:
{
// โฆ
"scripts": {
// โฆ
"format": "remark . --quiet --frail --output",
// โฆ
},
"remarkConfig": {
"plugins": [
"remark-validate-links"
]
},
// โฆ
}
๐ก Tip: Add other tools such as prettier or ESLint to check and format other files.
๐ก Tip: Run./node_modules/.bin/remark --help
for help withremark-cli
.
Now you check and format markdown in your project with:
npm run format
Integration
remark-validate-links
can detect anchors on nodes through several properties
on nodes:
node.data.hProperties.name
โ Used bymdast-util-to-hast
to create aname
attribute, which anchors can link tonode.data.hProperties.id
โ Used bymdast-util-to-hast
to create anid
attribute, which anchors can link tonode.data.id
โ Used potentially in the future by other tools to signal unique identifiers on nodes
Types
This package is fully typed with TypeScript.
It exports an Options
type, which specifies the interface of the accepted
options, and an UrlConfig
type, which specifies the interface of its
corresponding option.
Compatibility
Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.
This plugin works with unified
version 6+, remark
version 7+, and
remark-cli
version 8+.
Security
remark-validate-links
, in Node, accesses the file system based on user
content, and this may be dangerous.
In Node git remote
and git rev-parse
also runs for processed files.
The tree is not modified, so there are no openings for cross-site scripting (XSS) attacks.
Related
remark-lint
โ markdown code style linterremark-lint-no-dead-urls
โ check that external links are alive
Contribute
See contributing.md
in remarkjs/.github
for ways
to get started.
See support.md
for ways to get help.
This project has a code of conduct. By interacting with this repository, organization, or community you agree to abide by its terms.
License
MIT ยฉ Titus Wormer