Europa Node is a library for converting HTML into
valid Markdown within Node.js.
cheerio is used to parse HTML input without the need for complexity.
Install
Install using your preferred package manager. For example;
$ npm install --save node-europa
You'll need to have at least Node.js 12.22.0 or newer.
Check out europa,
europa-worker, or
europa-cli if you want to install it for use within
a web browser, worker, or as a CLI respectively.
Examples
import Europa from 'node-europa';
import * as express from 'express';
const app = express();
const europa = new Europa();
app.get('/md', (req, res) => {
res.set('Content-Type', 'text/markdown; charset=utf-8');
res.send(europa.convert('<a href="https://github.com/neocotic/europa">Europa</a>'));
});
app.listen(3000);
API
Simply create an instance of Europa and you've done most of the work. You can control many aspects of the HTML to
Markdown conversion by passing the following options to the constructor:
| Option | Type | Description | Default |
|---|
absolute | Boolean | Whether absolute URLs should be used for elements (e.g. anchors, images) | false |
baseUri | String | The base URI used to resolve relative URLs used for elements (e.g. anchors, images) | file://${process.cwd()} |
eol | String | The end of line character to be inserted into generated Markdown | os.EOL |
inline | Boolean | Whether URLs for elements (e.g. anchors, images) are to be inserted inline | false |
const europa = new Europa({
absolute: true,
baseUri: 'https://example.com',
eol: '\r\n',
inline: true,
});
convert(input)
Converts the specified input into Markdown.
input can either be an HTML string or DOM node(s) to be converted into Markdown. For a DOM node to be converted, it
must be compatible with the AnyNode type as declared in the domhandler
package to ensure that it works. This can be easily done using cheerio, which helps power
Europa Node under-the-hood.
const europa = new Europa();
europa.convert('<blockquote><b>Europa</b> is great!</blockquote>');
//=> "> **Europa** is great!"
europa.convert($('.lead')[0]);
//=> "_Everyone_ ♥ **Europa**!"
europa.convert($('<div>').html('Please keep my <span style="display: none">treasure</span> secret safe...')[0]);
//=> "Please keep my secret safe..."
Plugins
Europa is fully pluggable and is packed with default plugins in order to get full support for basic Markdown. It
enables the creation of external plugins to further extend Europa's capabilities to support extended Markdown syntax or
even new HTML elements should they not be added to Europa quick enough for you.
Plugins are packaged independently, however, the default plugins are included in
europa-preset-default and is bundled with
Europa Core so that they are available to all
implementations with no extra effort.
The API for plugins is simple on a high level, but you'll need to get to grips with the internal API to understand what
you can really do:
import { Plugin, PluginApi } from 'europa-core';
import Europa from 'node-europa';
const examplePluginProvider = (api: PluginApi): Plugin => ({
// All fields and methods are optional
converters: {
TAGNAME: {
startTag(conversion, context): boolean { /* ... */ },
endTag(conversion, context) { /* ... */ },
},
},
convertText(value, conversion): boolean { /* ... */ },
startConversion(conversion) { /* ... */ },
endConversion(conversion) { /* ... */ },
});
Europa.registerPlugin(examplePluginProvider);
It's highly recommended to look at existing plugins to get a better understanding of how things work.
Since multiple plugins could support the same tag(s), the load order is important as the last plugin loaded that
declares support for a tag, will be the one that's used. Be wary of overriding tags supported by default plugins and
consider whether it's something that should be part of the original plugin. If so, open a pull request!
A good practice for naming plugin packages is europa-plugin-<markdown-feature>. For example; europa-plugin-link and
not europa-plugin-a, and europa-plugin-quote and not europa-plugin-q. Each plugin should aim to support a specific
Markdown feature.
Take a look at Europa Build to quickly generate a
Europa plugin package.
Presets
Europa also has the concept of a "preset", which is essentially a bundle of plugins. In fact, all the default plugins
are provided by a default preset.
A preset simply imports a collection of plugins and declares them so that they can be registered together. For example;
import { PluginApi, PluginProvider, Preset } from 'europa-core';
import examplePluginProvider from 'europa-plugin-example';
import Europa from 'node-europa';
const pluginProviders: PluginProvider[] = [
examplePluginProvider,
// ...
];
const examplePresetProvider = (api: PluginApi): Preset => ({
// All fields and methods are optional
plugins: pluginProviders.map((pluginProvider) => pluginProvider(api)),
});
Europa.registerPreset(examplePresetProvider);
A good practice for naming preset packages is europa-preset-<markdown-feature-set>. For example;
europa-preset-github could be used to register plugins that converts HTML to GitHub-flavoured Markdown. Each preset
should include plugins that aim to support a related Markdown feature set.
Take a look at Europa Build to quickly generate a
Europa preset package.
Bugs
If you have any problems with Europa Node or would like to see changes currently in development you can do so
here.
Contributors
If you want to contribute, you're a legend! Information on how you can do so can be found in
CONTRIBUTING.md. We want your suggestions and pull
requests!
A list of Europa contributors can be found in AUTHORS.md.
License
Copyright © 2022 neocotic
See LICENSE.md for more information on
our MIT license.
