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 we’d link to it ([welcome](#hello)), we’d 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.
This is specifically for Git repos. Like this one. Not for say a website.
- What is this?
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This package is a unified (remark) plugin to check local links in a Git repo.
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
they’re 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).
This package is ESM only. In Node.js (version 16+), install with npm:
npm install remark-validate-linksIn Deno with esm.sh:
import remarkValidateLinks from 'https://esm.sh/remark-validate-links@13'In browsers with esm.sh:
<script type="module">
import remarkValidateLinks from 'https://esm.sh/remark-validate-links@13?bundle'
</script>Say we have the following file example.md in this project:
# Alpha
Links are checked:
This [exists](#alpha).
This [one does not](#apha).
# 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 {remark} from 'remark'
import remarkValidateLinks from 'remark-validate-links'
import {read} from 'to-vfile'
import {reporter} from 'vfile-reporter'
const file = await remark()
.use(remarkValidateLinks)
.process(await read('example.md'))
console.log(reporter(file))…then running node example.js yields:
example.md
6:6-6:27 warning Cannot find heading for `#apha`; did you mean `alpha` missing-heading remark-validate-links:missing-heading
11:5-11:53 warning Cannot find file `missing-example.js` missing-file remark-validate-links:missing-file
16:1-16:20 warning Cannot find heading for `#charlie` missing-heading remark-validate-links:missing-heading
⚠ 3 warnings👉 Note:
readme.md#no-such-headingis not warned about on the API, as it does not check headings in other markdown files. The remark CLI is able to do that.
This package exports no identifiers.
The default export is remarkValidateLinks.
Check that markdown links and images point to existing local files and headings in a Git repo.
⚠️ 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(Options, optional) — configuration
Transform (Transformer).
Configuration (TypeScript type).
repository(stringorfalse, default: detected from Git remote) — URL to hosted Git; if you’re not in a Git repository, you must passfalse; if the repository resolves to something npm understands as a Git host such as GitHub, GitLab, or Bitbucket, full URLs to that host (say,https://github.com/remarkjs/remark-validate-links/readme.md#install) are checkedroot(string, default: local Git folder) — path to Git root folder; if bothrootandrepositoryare nullish, the Git root is detected; ifrootis not given butrepositoryis,file.cwdis usedurlConfig(UrlConfig, default: detected from repo) — config on how hosted Git works;github.com,gitlab.com, orbitbucket.orgwork automatically; otherwise, passurlConfigmanually
Hosted Git info (TypeScript type).
headingPrefix(string, optional, example:'#','#markdown-header-') — prefix of headingshostname(string, optional, example:'github.com','bitbucket.org') — domain of URLslines(boolean, default:false) — whether lines in files can be linkedpath(string, optional, example:'/remarkjs/remark-validate-links/blob/','/remarkjs/remark-validate-links/src/') — path prefix before filestopAnchor(string, optional, example:#readme) — hash to top of readme
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
}It’s recommended to use remark-validate-links on the CLI with
remark-cli.
Install both with npm:
npm install remark-cli remark-validate-links --save-devLet’s 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 doesn’t 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
⚠ 2 warningsYou 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-devThen, add a format script and configuration to package.json:
{
// …
"scripts": {
// …
"format": "remark . --quiet --frail --output",
// …
},
"remarkConfig": {
"plugins": [
"remark-validate-links"
]
},
// …
}💡 Tip: Add other tools such as prettier or ESLint to check and format other files.
💡 Tip: Run
./node_modules/.bin/remark --helpfor help withremark-cli.
Now you check and format markdown in your project with:
npm run formatremark-validate-links can detect anchors on nodes through several properties
on nodes:
node.data.hProperties.name— Used bymdast-util-to-hastto create anameattribute, which anchors can link tonode.data.hProperties.id— Used bymdast-util-to-hastto create anidattribute, which anchors can link tonode.data.id— Used potentially in the future by other tools to signal unique identifiers on nodes
This package is fully typed with TypeScript.
It exports the additional types Options and
UrlConfig.
Projects maintained by the unified collective are compatible with maintained versions of Node.js.
When we cut a new major release, we drop support for unmaintained versions of
Node.
This means we try to keep the current release line,
remark-validate-links@^13, compatible with Node.js 16.
This plugin works with unified version 6+, remark version 7+, and
remark-cli version 8+.
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.
remark-lint— markdown code style linterremark-lint-no-dead-urls— check that external links are alive
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.
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