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https://github.com/activescott/agentmarkdown
An accurate, extensible, and fast HTML-to-markdown converter.
https://github.com/activescott/agentmarkdown
css html javascript markdown markdown-converter typescript user-agent
Last synced: about 1 month ago
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An accurate, extensible, and fast HTML-to-markdown converter.
- Host: GitHub
- URL: https://github.com/activescott/agentmarkdown
- Owner: activescott
- License: mpl-2.0
- Created: 2019-06-24T01:20:36.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-09-17T07:22:08.000Z (2 months ago)
- Last Synced: 2024-09-29T23:22:56.278Z (about 2 months ago)
- Topics: css, html, javascript, markdown, markdown-converter, typescript, user-agent
- Language: TypeScript
- Homepage: https://agentmarkdown.now.sh
- Size: 3.64 MB
- Stars: 9
- Watchers: 2
- Forks: 1
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- Contributing: .github/CONTRIBUTING.md
- License: LICENSE
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# Agent Markdown
An accurate, extensible, and fast HTML-to-markdown converter.
Agent Markdown is a [HTML user agent](https://en.wikipedia.org/wiki/User_agent) that parses HTML, performs a document layout according to the [CSS stylesheet for HTML](https://html.spec.whatwg.org/multipage/rendering.html#the-css-user-agent-style-sheet-and-presentational-hints) and then "renders" the laid out document to Markdown. This results in markdown that looks very similar to the way the HTML document looked when parsed and rendered in a browser (user agent).
- [Usage / Quick Start](#usage--quick-start)
- [Install](#install)
- [Features](#features)
- [CLI Example](#cli-example)
- [Live Example](#live-example)
- [Customize & Extend with Plugins](#customize--extend-with-plugins)
- [Show your support](#show-your-support)
- [Contributing 🤝](#contributing-🤝)
- [Release Process (Deploying to NPM) 🚀](#release-process-deploying-to-npm-🚀)
- [License 📝](#license-📝)
## Usage / Quick Start
```
import { AgentMarkdown } from "agentmarkdown"
const markdownString = await AgentMarkdown.produce(htmlString)
```
## Install
npm (`npm install agentmarkdown`)
## Features
- Accurately converts HTML to [CommonMark-compliant](https://commonmark.org/) markdown
- uses [GitHub-Flavored Markdown's Strikethrough extention](https://github.github.com/gfm/#strikethrough-extension-) for <strike> and <del>.
- Supports even wonky technically incorrect HTML
- Supports nested lists
- Supports [implied paragraphs](https://html.spec.whatwg.org/#paragraphs) / [CSS anonymous bock box layout](https://www.w3.org/TR/CSS22/visuren.html#anonymous-block-level)
- Can be used client side (in the browser) or server side (with Node.js)
- Add support for new elements [with plugins](#customize--extend-with-plugins)
- Fast?
## CLI Example
You can convert any HTML file to Markdown at the command line using the following command, and the markdown output will be printed to stdout:
agentmarkdown
It also responds to stdin, if you pipe html to it. So you can do things like:
echo "bold" | agentmarkdown > myfile.md
The above commands assume you installed agentmarkdown with `npm install --global agentmarkdown` but it also works with `npx` so you can run it without installing like:
npx agentmarkdown
## Live Example
You can view the live online web example at [https://agentmarkdown.now.sh](https://agentmarkdown.now.sh).
You can build and the web example locally with the following commands:
```
cd example/
npm install
npm run start
```
_NOTE: If you have trouble starting the example on macOS related to `fsevents` errors, it may require running `xcode-select --install`. If that doesn't work, then possibly a `sudo rm -rf $(xcode-select -print-path)` followed by `xcode-select --install` will be necessary._
## Customize & Extend with Plugins
To customize how the markdown is generated or add support for new elements, implement the `LayoutPlugin` interface to handle a particular HTML element. The `LayoutPlugin` interface is defined as follows:
```TypeScript
export interface LayoutPlugin {
/**
* Specifies the name of the HTML element that this plugin renders markdown for.
* NOTE: Must be all lowercase
*/
elementName: string
/**
* This is the core of the implementation that will be called for each instance of the HTML element that this plugin is registered for.
*/
layout: LayoutGenerator
}
```
The `LayoutGenerator` is a single function that performs a [CSS2 box generation layout algorithm](https://www.w3.org/TR/CSS22/visuren.html#box-gen) on the an HTML element. Essentially it creates zero or more boxes for the given element that AgentMarkdown will render to text. A box can contain text content and/or other boxes, and each box has a type of `inline` or `block`. Inline blocks are laid out horizontally. Block boxes are laid out vertically (i.e. they have new line characters before and after their contents). The `LayoutGenerator` function definition is as follows:
```TypeScript
export interface LayoutGenerator {
(
context: LayoutContext,
manager: LayoutManager,
element: HtmlNode
): CssBox | null
}
```
An example of how the HTML `` element could be implemented as a plugin like the following:
```TypeScript
class BoldPlugin {
elementName: "b"
layout: LayoutGenerator = (
context: LayoutContext,
manager: LayoutManager,
element: HtmlNode
): CssBox | null => {
// let the manager use other plugins to layout any child elements:
const kids = manager.layout(context, element.children)
// wrap the child elements in the markdown ** syntax for bold/strong:
kids.unshift(manager.createBox(BoxType.inline, "**"))
kids.push(manager.createBox(BoxType.inline, "**"))
// return a new box containing everything:
return manager.createBox(BoxType.inline, "", kids)
}
}
```
To initialize AgentMarkdown with plugins pass them in as an array value for the `layoutPlugins` option as follows. To customize the rendering an element you can just specify a plugin for the elementName and your plugin will override the built-in plugin.
```TypeScript
const result = await AgentMarkdown.render({
html: myHtmlString,
layoutPlugins: [
new BoldPlugin()
]
})
```
## Show your support
Please give a ⭐️ if this project helped you!
## Contributing 🤝
This is a community project. We invite your participation through issues and pull requests! You can peruse the [contributing guidelines](.github/CONTRIBUTING.md).
# Building
The package is written in TypeScript. To build the package run the following from the root of the repo:
npm run build # It will be built in /dist
## Release Process (Deploying to NPM) 🚀
We use [semantic-release](https://github.com/semantic-release/semantic-release) to consistently release [semver](https://semver.org/)-compatible versions. This project deploys to multiple [npm distribution tags](https://docs.npmjs.com/cli/dist-tag). Each of the below branches correspond to the following npm distribution tags:
| branch | npm distribution tag |
| ------ | -------------------- |
| master | latest |
| beta | beta |
To trigger a release use a Conventional Commit following [Angular Commit Message Conventions](https://github.com/angular/angular.js/blob/master/DEVELOPERS.md#-git-commit-guidelines) on one of the above branches.
# Todo / Roadmap
see [/docs/todo.md](docs/todo.md)
# Alternatives
- http://domchristie.github.io/turndown/
- https://github.com/rehypejs/rehype-remark
## License 📝
Copyright © 2019 [Scott Willeke](https://github.com/activescott).
This project is licensed via [Mozilla Public License 2.0](https://github.com/activescott/agentmarkdown/blob/master/LICENSE).