markdown 2.1.5

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A portable Markdown library written in Dart. It can parse Markdown into HTML on both the client and server.

Play with it at

Usage #

import 'package:markdown/markdown.dart';

void main() {
  print(markdownToHtml('Hello *Markdown*'));
  //=> <p>Hello <em>Markdown</em></p>

Syntax extensions #

A few Markdown extensions, beyond what was specified in the original Perl Markdown implementation, are supported. By default, the ones supported in CommonMark are enabled. Any individual extension can be enabled by specifying an Array of extension syntaxes in the blockSyntaxes or inlineSyntaxes argument of markdownToHtml.

The currently supported inline extension syntaxes are:

  • new InlineHtmlSyntax() - approximately CommonMark's definition of "Raw HTML".

The currently supported block extension syntaxes are:

  • const FencedCodeBlockSyntax() - Code blocks familiar to Pandoc and PHP Markdown Extra users.
  • const HeaderWithIdSyntax() - ATX-style headers have generated IDs, for link anchors (akin to Pandoc's auto_identifiers).
  • const SetextHeaderWithIdSyntax() - Setext-style headers have generated IDs for link anchors (akin to Pandoc's auto_identifiers).
  • const TableSyntax() - Table syntax familiar to GitHub, PHP Markdown Extra, and Pandoc users.

For example:

import 'package:markdown/markdown.dart';

void main() {
  print(markdownToHtml('Hello <span class="green">Markdown</span>',
      inlineSyntaxes: [new InlineHtmlSyntax()]));
  //=> <p>Hello <span class="green">Markdown</span></p>

Extension sets #

To make extension management easy, you can also just specify an extension set. Both markdownToHtml() and new Document() accept an extensionSet named parameter. Right now there are two extension sets:

  • ExtensionSet.none includes no extensions. With no extensions, Markdown documents will be parsed closely to how they might be parsed by the original Perl Markdown implementation.

  • ExtensionSet.commonMark includes two extensions so far, which bring this package's Markdown parsing closer to what is found in the CommonMark spec:

    • new InlineHtmlSyntax()
    • const FencedCodeBlockSyntax()
  • ExtensionSet.gitHubWeb includes seven extensions:

    • new EmojiSyntax()
    • new InlineHtmlSyntax()
    • const HeaderWithIdSyntax(), which adds id attributes to ATX-style headers, for easy intra-document linking.
    • const SetextHeaderWithIdSyntax(), which adds id attributes to Setext-style headers, for easy intra-document linking.
    • const FencedCodeBlockSyntax()
    • new StrikethroughSyntax()
    • const TableSyntax()

Custom syntax extensions #

You can create and use your own syntaxes.

import 'package:markdown/markdown.dart';

void main() {
  var syntaxes = [new TextSyntax('nyan', sub: '~=[,,_,,]:3')];
  print(markdownToHtml('nyan', inlineSyntaxes: syntaxes));
  //=> <p>~=[,,_,,]:3</p>

HTML sanitization #

This package offers no features in the way of HTML sanitization. Read Estevão Soares dos Santos's great article, "Markdown's XSS Vulnerability (and how to mitigate it)", to learn more.

The authors recommend that you perform any necessary sanitization on the resulting HTML, for example via dart:html's NodeValidator.

CommonMark compliance #

This package contains a number of files in the tool directory for tracking compliance with CommonMark.

Updating CommonMark stats when changing the implementation

  1. Update the library and test code, making sure that tests still pass.
  2. Run dart tool/stats.dart --update-files to update the per-test results tool/common_mark_stats.json and the test summary tool/common_mark_stats.txt.
  3. Verify that more tests now pass – or at least, no more tests fail.
  4. Make sure you include the updated stats files in your commit.

Updating the CommonMark test file for a spec update

  1. Check out the CommonMark source. Make sure you checkout a major release.

  2. Dump the test output overwriting the existing tests file.

    > cd /path/to/common_mark_dir
    > python3 test/ --dump-tests > \
  3. Update the stats files as described above. Note any changes in the results.

  4. Update any references to the existing spec by search for in the repository. (Including this one.) Verify the updated links are still valid.

  5. Commit changes, including a corresponding note in

2.1.5 #

  • Overhaul table row parsing. This does not have many consequences, except that whitespace around escaped pipes is handled better. (#287).

2.1.4 #

  • Correctly parse a reference link with a newline in the link reference part (#281).

2.1.3 #

  • Do not encode HTML in link URLs. Also do not encode HTML in link text when encodeHtml is false (e.g. when used in Flutter).

2.1.2 #

  • Drop support for Dart 2.0.0 through 2.1.0.
  • Recognize Unicode ellipsis (…) and other Unicode punctuation as punctuation when parsing potential emphasis.
  • Reduce time to parse a large HTML-block-free Markdown document (such as that in #271) by more than half.
  • Add a new optional parameter for InlineSyntax(), startCharacter, where a subclass can specify a single character to try to match, before matching with more expensive regular expressions.

2.1.1 #

  • Fix for encoding HTML for text string that contains <pre> (#263).

2.1.0 #

  • Improve strict spec compliance of > handling by always encoding as &gt; – unless preceded by /.
  • Improve strict spec compliance for blockquote by always putting the closing tag on a new line.
  • Improve strict spec compliance for code elements defined with "`".
  • Properly encode <, >, and " as their respective HTML entities when interpreted as text.
  • Improve inline code parsing when using multiple backticks.
  • Do not encode HTML in indented code blocks when encodeHtml is false (e.g. when used in Flutter).

2.0.3 #

  • Render element attributes in the order they were defined. Aligns more closely with the strict spec definition.
  • Correctly render & within inline image titles.
  • Add 68 new GitHub emojis.
  • Escape HTML attribute for fenced code blocks, in the info string.

2.0.2 #

  • Set max SDK version to <3.0.0, and adjust other dependencies.

2.0.1 #

  • Require Dart 2.0.0-dev.

2.0.0 #

  • Breaking change: The Link class has been renamed LinkReference, and the Document field, refLinks, has been renamed linkReferences.

  • Breaking change: Remove the deprecated ExtensionSet.gitHub field. Use ExtensionSet.gitHubFlavored instead.

  • Breaking change: Make all of the fields on Document read-only.

  • Overhaul support for emphasis (*foo* and _foo_) and strong emphasis (**foo** and __foo__), dramatically improving CommonMark compliance.

  • Overhaul support for links and images, again dramatically improving CommonMark compliance.

  • Improve support for tab characters, and horizontal rules.

  • Add support for GitHub Flavored Markdown's Strikethrough extension. See the GFM spec.

  • The above fixes raise compliance with the CommonMark specs to 93%, and compliance with the GFM specs to 92%.

  • Add an encodeHtml parameter to Document, which defaults to true. When false, HTML entities (such as &copy; and the < character) will not be escaped, useful when rendering Markdown in some output format other than HTML.

  • Allow the binary script to take a --extension-set option.

    A reminder: You can run bin/markdown.dart from anywhere via:

    $ pub global activate markdown
    $ markdown

1.1.1 #

  • Add support for GitHub's colon-based Emoji syntax. 🎉! This is available in the gitHubWeb extension set.

1.1.0 #

  • Make the constructor for ExtensionSet public, for tools like dartdoc.
  • Split the gitHub ExtensionSet into two sets: gitHubFlavored, which represents the GitHub Flavored Markdown spec, and gitHubWeb, which represents what GitHub actually renders Markdown.

1.0.0 #

  • Fix issue where accept could cause an exception.
  • Remove deprecated escapeHtml function.
  • Fix compliance with auto-links, including support for email addresses.
  • Updated ExtensionSet.gitHub to more closely align with GitHub markdown.

0.11.4 #

  • Fix bug with lazy blockquote continuations (#162)
  • Fix bug with list item continuations (#156)

0.11.3 #

  • Deprecate escapeHtml. This code exists in dart:convert.

0.11.2 #

  • Fix reference code links inside blockquotes.
  • Add src/util.dart to exports.

0.11.1 #

  • Add version information:
    • dart bin/markdown.dart --version now shows the package version number.
    • The playground app now shows the version number.
  • Improve autolink parsing.
  • Add new table syntax: TableSyntax.
  • Add new ExtensionSet that includes the table syntax: ExtensionSet.gitHub.
  • For development: added tool/
  • Support multiline Setext headers.
  • Handle loose-vs-strict list items better.
  • Support ordered lists that start with a number other than 1.

0.11.0+1 #

0.11.0 #

  • Parse HTML blocks more accurately, according to CommonMark.
  • Support shortcut reference links.
  • Don't allow an indented code block to interrupt a paragraph.
  • Change definition of "loose" and "strict" lists (items wrapped in paragraph tags vs not) to CommonMark's. The primary difference is that any single list item can trigger the entire list to be marked as "loose", rather than defining "looseness" on each specific item.
  • Fix paragraph continuations in blockquotes and list items.
  • Fix silly typing bug with tool/common_mark_stats.dart, which resulted in a dramatic overestimate of our CommonMark compliance.
  • There are now 427/613 (69%) passing CommonMark v0.25 specs.

0.10.1 #

  • Parse hard line breaks properly (#86). Thanks @mehaase!
  • Fix processing of [ ... ] syntax when no resolver is specified (#92).
  • There are now 401/613 (65%) passing CommonMark v0.24 specs. (Actually: after 0f64c8f the actual number of passing tests was 352/613 (57%).)

0.10.0 #

  • BREAKING: Now following the CommonMark spec for fenced code blocks. If a language (info string) is provided, it is added as a class to the code element with a language- prefix.
  • BREAKING: Now following the CommonMark spec for images. Previously, ![text](img.png) would compile too <a href="img.prg"><img src="img.prg" alt="text"></img></a>. That same code will now compile to <img src="img.png" alt="text" />.
  • Fix all strong mode errors.

0.9.0 #

  • BREAKING: The text [foo] (bar) no longer renders as an inline link (#53).
  • BREAKING: Change list parsing to allow lists to begin immediately after a preceding block element, without a blank line in between.
  • Formalize an API for Markdown extensions (#43).
  • Introduce ExtensionSets. FencedCodeBlock is considered an extension, but existing usage of markdownToHtml() and new Document() will use the default extension set, which is ExtensionSet.commonMark, which includes FencedCodeBlock.
  • Inline HTML syntax support; This is also considered an extension (#18).
  • The text [foo]() now renders as an inline link.
  • Whitespace now allowed between a link's destination and title (#65).
  • Header identifier support in the HeaderWithIdSyntax and SetextHeaderWithIdSyntax extensions.
  • Implement backslash-escaping so that Markdown syntax can be escaped, such as [foo]\(bar) ==> <p>[foo](bar)</p>.
  • Support for hard line breaks with either \\\n or \n (#30, #60).
  • New public method for BlockParser: peek(int linesAhead), meant for use in subclasses.
  • New public members for ListSyntax: blocksInList and determineBlockItems(), meant for use in subclasses.
  • Improve public docs (better, and more of them).

0.8.0 #

  • Breaking: Remove (probably unused) fields: LinkSyntax.resolved, InlineParser.currentSource.
  • Switch tests to use test instead of unittest.
  • Fix a few bugs in inline code syntax.
  • Ignore underscores inside words (#41).

0.7.2 #

  • Allow resolving links that contain inline syntax (#42).

0.7.1+3 #

  • Updated homepage.

0.7.1+2 #

  • Formatted code.

  • Updated readme.

Use this package as an executable

1. Install it

You can install the package from the command line:

$ pub global activate markdown

2. Use it

The package has the following executables:

$ markdown

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  markdown: ^2.1.5

2. Install it

You can install packages from the command line:

with pub:

$ pub get

with Flutter:

$ flutter pub get

Alternatively, your editor might support pub get or flutter pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:markdown/markdown.dart';
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Learn more about scoring.

We analyzed this package on Jul 2, 2020, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.8.4
  • pana: 0.13.13

Maintenance suggestions

The package description is too short. (-18 points)

Add more detail to the description field of pubspec.yaml. Use 60 to 180 characters to describe the package, what it does, and its target use case.

Maintain an example.

None of the files in the package's example/ directory matches known example patterns.

Common filename patterns include main.dart, example.dart, and markdown.dart. Packages with multiple examples should provide example/

For more information see the pub package layout conventions.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=2.6.0 <3.0.0
args ^1.0.0 1.6.0
charcode ^1.1.0 1.1.3
Dev dependencies
build_runner ^1.0.0
build_version ^2.0.0
build_web_compilers >=1.0.0 <3.0.0
collection ^1.2.0
expected_output ^1.2.1
html >=0.12.2 <0.15.0
io ^0.3.2+1
js ^0.6.1
path ^1.3.1
pedantic ^1.9.0
test ^1.2.0
yaml ^2.1.8