rehype-external-links
rehype plugin to add rel (and target) to external links.
Contents
What is this?
This package is a unified (rehype) plugin to add rel (and target)
attributes to external links.
It is particularly useful when displaying user content on your reputable site,
because users could link to disreputable sources (spam, scams, etc), as search
engines and other bots will discredit your site for linking to them (or
legitimize their sites).
In short: linking to something signals trust, but you can’t trust users.
This plugin adds certain rel attributes to prevent that from happening.
unified is a project that transforms content with abstract syntax trees
(ASTs).
rehype adds support for HTML to unified.
hast is the HTML AST that rehype uses.
This is a rehype plugin that adds rel (and target) to <a>s in the AST.
When should I use this?
This project is useful when you want to display user content from authors you
don’t trust (such as comments), as they might include links you don’t endorse,
on your website.
Install
This package is ESM only.
In Node.js (version 16+), install with npm:
npm install rehype-external-links
In Deno with esm.sh:
import rehypeExternalLinks from 'https://esm.sh/rehype-external-links@3'
In browsers with esm.sh:
<script type="module">
import rehypeExternalLinks from 'https://esm.sh/rehype-external-links@3?bundle'
</script>
Use
Say our module example.js contains:
import rehypeExternalLinks from 'rehype-external-links'
import remarkParse from 'remark-parse'
import remarkRehype from 'remark-rehype'
import rehypeStringify from 'rehype-stringify'
import {unified} from 'unified'
const file = await unified()
.use(remarkParse)
.use(remarkRehype)
.use(rehypeExternalLinks, {rel: ['nofollow']})
.use(rehypeStringify)
.process('[rehype](https://github.com/rehypejs/rehype)')
console.log(String(file))
…then running node example.js yields:
<p><a href="https://github.com/rehypejs/rehype" rel="nofollow">rehype</a></p>
API
This package exports no identifiers.
The default export is rehypeExternalLinks.
unified().use(rehypeExternalLinks[, options])
Automatically add rel (and target?) to external links.
Parameters
options (Options, optional)
— configuration
Returns
Transform (Transformer).
Notes
You should likely not configure target.
You should at least set rel to ['nofollow'].
When using a target, add noopener and noreferrer to avoid exploitation
of the window.opener API.
When using a target, you should set content to adhere to accessibility
guidelines by giving users advanced warning when opening a new window.
CreateContent
Create a target for the element (TypeScript type).
Parameters
element (Element)
— element to check
Returns
Content to add (Array<Node> or Node, optional).
CreateProperties
Create properties for an element (TypeScript type).
Parameters
element (Element)
— element to check
Returns
Properties to add (Properties, optional).
CreateRel
Create a rel for the element (TypeScript type).
Parameters
element (Element)
— element to check
Returns
rel to use (Array<string>, optional).
CreateTarget
Create a target for the element (TypeScript type).
Parameters
element (Element)
— element to check
Returns
target to use (Target, optional).
Options
Configuration (TypeScript type).
Fields
content (Array<Node>, CreateContent, or Node,
optional)
— content to insert at the end of external links; will be inserted in a
<span> element; useful for improving accessibility by giving users
advanced warning when opening a new windowcontentProperties (CreateProperties or
Properties, optional)
— properties to add to the span wrapping contentproperties (CreateProperties or
Properties, optional)
— properties to add to the link itselfprotocols (Array<string>, default: ['http', 'https'])
— protocols to see as external, such as mailto or telrel (Array<string>, CreateRel, or string,
default: ['nofollow'])
— link types to hint about the referenced documents; pass an
empty array ([]) to not set rels on links; when using a target, add noopener
and noreferrer to avoid exploitation of the window.opener APItarget (CreateTarget or Target,
optional)
— how to display referenced documents; the default (nothing) is to not set
targets on linkstest (Test, optional)
— extra test to define which external link elements are modified; any test
that can be given to hast-util-is-element is supported
Target
Target (TypeScript type).
Type
type Target = '_blank' | '_parent' | '_self' | '_top'
Types
This package is fully typed with TypeScript.
It exports the additional types
CreateContent,
CreateProperties,
CreateRel,
CreateTarget,
Options, and
Target.
Compatibility
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, rehype-external-links@^3,
compatible with Node.js 16.
This plugin works with rehype-parse version 3+, rehype-stringify version 3+,
rehype version 4+, and unified version 6+.
Security
Improper use of rehype-external-links can open you up to a
cross-site scripting (XSS) attack.
Either do not combine this plugin with user content or use
rehype-sanitize.
Contribute
See contributing.md in rehypejs/.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 © Titus Wormer
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