# micromark-extension-gfm-autolink-literal [![Build][build-badge]][build] [![Coverage][coverage-badge]][coverage] [![Downloads][downloads-badge]][downloads] [![Size][size-badge]][size] [![Sponsors][sponsors-badge]][collective] [![Backers][backers-badge]][collective] [![Chat][chat-badge]][chat] [micromark][] extensions to support GFM [literal autolinks][spec]. ## Contents * [What is this?](#what-is-this) * [When to use this](#when-to-use-this) * [Install](#install) * [Use](#use) * [API](#api) * [`gfmAutolinkLiteral()`](#gfmautolinkliteral) * [`gfmAutolinkLiteralHtml()`](#gfmautolinkliteralhtml) * [Bugs](#bugs) * [Authoring](#authoring) * [HTML](#html) * [CSS](#css) * [Syntax](#syntax) * [Types](#types) * [Compatibility](#compatibility) * [Security](#security) * [Related](#related) * [Contribute](#contribute) * [License](#license) ## What is this? This package contains extensions that add support for the extra autolink syntax enabled by GFM to [`micromark`][micromark]. GitHub employs different algorithms to autolink: one at parse time and one at transform time (similar to how @mentions are done at transform time). This difference can be observed because character references and escapes are handled differently. But also because issues/PRs/comments omit (perhaps by accident?) the second algorithm for `www.`, `http://`, and `https://` links (but not for email links). As this is a syntax extension, it focuses on the first algorithm. The second algorithm is performed by [`mdast-util-gfm-autolink-literal`][mdast-util-gfm-autolink-literal]. The `html` part of this micromark extension does not operate on an AST and hence can’t perform the second algorithm. The implementation of autolink literal on github.com is currently buggy. The bugs have been reported on [`cmark-gfm`][cmark-gfm]. This micromark extension matches github.com except for its bugs. ## When to use this This project is useful when you want to support autolink literals in markdown. You can use these extensions when you are working with [`micromark`][micromark]. To support all GFM features, use [`micromark-extension-gfm`][micromark-extension-gfm] instead. When you need a syntax tree, combine this package with [`mdast-util-gfm-autolink-literal`][mdast-util-gfm-autolink-literal]. All these packages are used in [`remark-gfm`][remark-gfm], which focusses on making it easier to transform content by abstracting these internals away. ## Install This package is [ESM only][esm]. In Node.js (version 16+), install with [npm][]: ```sh npm install micromark-extension-gfm-autolink-literal ``` In Deno with [`esm.sh`][esmsh]: ```js import {gfmAutolinkLiteral, gfmAutolinkLiteralHtml} from 'https://esm.sh/micromark-extension-gfm-autolink-literal@2' ``` In browsers with [`esm.sh`][esmsh]: ```html ``` ## Use ```js import {micromark} from 'micromark' import { gfmAutolinkLiteral, gfmAutolinkLiteralHtml } from 'micromark-extension-gfm-autolink-literal' const output = micromark('Just a URL: www.example.com.', { extensions: [gfmAutolinkLiteral()], htmlExtensions: [gfmAutolinkLiteralHtml()] }) console.log(output) ``` Yields: ```html

Just a URL: www.example.com.

``` ## API This package exports the identifiers [`gfmAutolinkLiteral`][api-gfm-autolink-literal] and [`gfmAutolinkLiteralHtml`][api-gfm-autolink-literal-html]. There is no default export. The export map supports the [`development` condition][development]. Run `node --conditions development module.js` to get instrumented dev code. Without this condition, production code is loaded. ### `gfmAutolinkLiteral()` Create an extension for `micromark` to support GitHub autolink literal syntax. ###### Parameters Extension for `micromark` that can be passed in `extensions` to enable GFM autolink literal syntax ([`Extension`][micromark-extension]). ### `gfmAutolinkLiteralHtml()` Create an HTML extension for `micromark` to support GitHub autolink literal when serializing to HTML. ###### Parameters Extension for `micromark` that can be passed in `htmlExtensions` to support GitHub autolink literal when serializing to HTML ([`HtmlExtension`][micromark-html-extension]). ## Bugs GitHub’s own algorithm to parse autolink literals contains three bugs. A smaller bug is left unfixed in this project for consistency. Two main bugs are not present in this project. The issues relating to autolink literals are: * [GFM autolink extension (`www.`, `https?://` parts): links don’t work when after bracket](https://github.com/github/cmark-gfm/issues/278)\ fixed here ✅ * [GFM autolink extension (`www.` part): uppercase does not match on issues/PRs/comments](https://github.com/github/cmark-gfm/issues/280)\ fixed here ✅ * [GFM autolink extension (`www.` part): the word `www` matches](https://github.com/github/cmark-gfm/issues/279)\ present here for consistency ## Authoring It is recommended to use labels, either with a resource or a definition, instead of autolink literals, as those allow relative URLs and descriptive text to explain the URL in prose. ## HTML GFM autolink literals relate to the `` element in HTML. See [*§ 4.5.1 The `a` element*][html-a] in the HTML spec for more info. When an email autolink is used, the string `mailto:` is prepended when generating the `href` attribute of the hyperlink. When a www autolink is used, the string `http://` is prepended. ## CSS As hyperlinks are the fundamental thing that makes the web, you will most definitely have CSS for `a` elements already. The same CSS can be used for autolink literals, too. GitHub itself does not apply interesting CSS to autolink literals. For any link, it currently (June 2022) [uses][css]: ```css a { background-color: transparent; color: #58a6ff; text-decoration: none; } a:active, a:hover { outline-width: 0; } a:hover { text-decoration: underline; } a:not([href]) { color: inherit; text-decoration: none; } ``` ## Syntax Autolink literals form with, roughly, the following BNF: ```bnf gfm_autolink_literal ::= gfm_protocol_autolink | gfm_www_autolink | gfm_email_autolink ; Restriction: the code before must be `www_autolink_before`. ; Restriction: the code after `.` must not be eof. www_autolink ::= 3('w' | 'W') '.' [domain [path]] www_autolink_before ::= eof | eol | space_or_tab | '(' | '*' | '_' | '[' | ']' | '~' ; Restriction: the code before must be `http_autolink_before`. ; Restriction: the code after the protocol must be `http_autolink_protocol_after`. http_autolink ::= ('h' | 'H') 2('t' | 'T') ('p' | 'P') ['s' | 'S'] ':' 2'/' domain [path] http_autolink_before ::= byte - ascii_alpha http_autolink_protocol_after ::= byte - eof - eol - ascii_control - unicode_whitespace - ode_punctuation ; Restriction: the code before must be `email_autolink_before`. ; Restriction: `ascii_digit` may not occur in the last label part of the label. email_autolink ::= 1*('+' | '-' | '.' | '_' | ascii_alphanumeric) '@' 1*(1*label_segment l_dot_cont) 1*label_segment email_autolink_before ::= byte - ascii_alpha - '/' ; Restriction: `_` may not occur in the last two domain parts. domain ::= 1*(url_ampt_cont | domain_punct_cont | '-' | byte - eof - ascii_control - ode_whitespace - unicode_punctuation) ; Restriction: must not be followed by `punct`. domain_punct_cont ::= '.' | '_' ; Restriction: must not be followed by `char-ref`. url_ampt_cont ::= '&' ; Restriction: a counter `balance = 0` is increased for every `(`, and decreased for every `)`. ; Restriction: `)` must not be `paren_at_end`. path ::= 1*(url_ampt_cont | path_punctuation_cont | '(' | ')' | byte - eof - eol - space_or_tab) ; Restriction: must not be followed by `punct`. path_punctuation_cont ::= trailing_punctuation - '<' ; Restriction: must be followed by `punct` and `balance` must be less than `0`. paren_at_end ::= ')' label_segment ::= label_dash_underscore_cont | ascii_alpha | ascii_digit ; Restriction: if followed by `punct`, the whole email autolink is invalid. label_dash_underscore_cont ::= '-' | '_' ; Restriction: must not be followed by `punct`. label_dot_cont ::= '.' punct ::= *trailing_punctuation ( byte - eof - eol - space_or_tab - '<' ) char_ref ::= *ascii_alpha ';' path_end trailing_punctuation ::= '!' | '"' | '\'' | ')' | '*' | ',' | '.' | ':' | ';' | '<' | '?' | '_' | '~' ``` The grammar for GFM autolink literal is very relaxed: basically anything except for whitespace is allowed after a prefix. To use whitespace characters and otherwise impossible characters, in URLs, you can use percent encoding: ```markdown https://example.com/alpha%20bravo ``` Yields: ```html

``` There are several cases where incorrect encoding of URLs would, in other languages, result in a parse error. In markdown, there are no errors, and URLs are normalized. In addition, many characters are percent encoded ([`sanitizeUri`][micromark-util-sanitize-uri]). For example: ```markdown www.a👍b% ``` Yields: ```html

www.a👍b%

``` There is a big difference between how www and protocol literals work compared to how email literals work. The first two are done when parsing, and work like anything else in markdown. But email literals are handled afterwards: when everything is parsed, we look back at the events to figure out if there were email addresses. This particularly affects how they interleave with character escapes and character references. ## Types This package is fully typed with [TypeScript][]. It exports no additional types. ## 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, `micromark-extension-gfm-autolink-literal@^2`, compatible with Node.js 16. This package works with `micromark` version `3` and later. ## Security This package is safe. Unlike other links in CommonMark, which allow arbitrary protocols, this construct always produces safe links. ## Related * [`micromark-extension-gfm`][micromark-extension-gfm] — support all of GFM * [`mdast-util-gfm-autolink-literal`][mdast-util-gfm-autolink-literal] — support all of GFM in mdast * [`mdast-util-gfm`][mdast-util-gfm] — support all of GFM in mdast * [`remark-gfm`][remark-gfm] — support all of GFM in remark ## Contribute See [`contributing.md` in `micromark/.github`][contributing] for ways to get started. See [`support.md`][support] for ways to get help. This project has a [code of conduct][coc]. By interacting with this repository, organization, or community you agree to abide by its terms. ## License [MIT][license] © [Titus Wormer][author] [build-badge]: https://github.com/micromark/micromark-extension-gfm-autolink-literal/workflows/main/badge.svg [build]: https://github.com/micromark/micromark-extension-gfm-autolink-literal/actions [coverage-badge]: https://img.shields.io/codecov/c/github/micromark/micromark-extension-gfm-autolink-literal.svg [coverage]: https://codecov.io/github/micromark/micromark-extension-gfm-autolink-literal [downloads-badge]: https://img.shields.io/npm/dm/micromark-extension-gfm-autolink-literal.svg [downloads]: https://www.npmjs.com/package/micromark-extension-gfm-autolink-literal [size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=micromark-extension-gfm-autolink-literal [size]: https://bundlejs.com/?q=micromark-extension-gfm-autolink-literal [sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg [backers-badge]: https://opencollective.com/unified/backers/badge.svg [collective]: https://opencollective.com/unified [chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg [chat]: https://github.com/micromark/micromark/discussions [npm]: https://docs.npmjs.com/cli/install [esmsh]: https://esm.sh [license]: license [author]: https://wooorm.com [contributing]: https://github.com/micromark/.github/blob/main/contributing.md [support]: https://github.com/micromark/.github/blob/main/support.md [coc]: https://github.com/micromark/.github/blob/main/code-of-conduct.md [esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c [typescript]: https://www.typescriptlang.org [development]: https://nodejs.org/api/packages.html#packages_resolving_user_conditions [micromark]: https://github.com/micromark/micromark [micromark-extension-gfm]: https://github.com/micromark/micromark-extension-gfm [micromark-util-sanitize-uri]: https://github.com/micromark/micromark/tree/main/packages/micromark-util-sanitize-uri [micromark-extension]: https://github.com/micromark/micromark#syntaxextension [micromark-html-extension]: https://github.com/micromark/micromark#htmlextension [mdast-util-gfm]: https://github.com/syntax-tree/mdast-util-gfm [mdast-util-gfm-autolink-literal]: https://github.com/syntax-tree/mdast-util-gfm-autolink-literal [remark-gfm]: https://github.com/remarkjs/remark-gfm [spec]: https://github.github.com/gfm/#autolinks-extension- [html-a]: https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-a-element [css]: https://github.com/sindresorhus/github-markdown-css [cmark-gfm]: https://github.com/github/cmark-gfm [api-gfm-autolink-literal]: #gfmautolinkliteral [api-gfm-autolink-literal-html]: #gfmautolinkliteralhtml

c	File Name	Size	T	Date
zip	dev/	4096	---	2026-06-10 03:36:21
zip	lib/	4096	---	2026-06-10 03:36:21
-	index.d.ts	427	ts	2026-05-20 11:21:44
-	index.js	104	js	2026-05-20 11:21:44
-	license	1099	%	2026-05-20 11:21:44
-	package.json	2889	json	2026-05-20 11:21:44
-	readme.md	13845	md	2026-05-20 11:21:44

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