metalsmith / headings

A Metalsmith plugin that extracts headings from HTML files and attaches them to the file's metadata.

Metalsmith

An extremely simple, pluggable static site generator for NodeJS.

In Metalsmith, all of the logic is handled by plugins. You simply chain them together.

Here's what the simplest blog looks like:

import { fileURLToPath } from 'node:url'
import { dirname } from 'path'
import Metalsmith from 'metalsmith'
import layouts from '@metalsmith/layouts'
import markdown from '@metalsmith/markdown'

const __dirname = dirname(fileURLToPath(import.meta.url))

Metalsmith(__dirname)
  .use(markdown())
  .use(
    layouts({
      pattern: '**/*.html'
    })
  )
  .build(function (err) {
    if (err) throw err
    console.log('Build finished!')
  })

Installation

NPM:

npm install metalsmith

Yarn:

yarn add metalsmith

Quickstart

What if you want to get fancier by hiding unfinished drafts, grouping posts in collections, and using custom permalinks? Just add plugins...

import { fileURLToPath } from 'node:url'
import { dirname } from 'node:path'
import Metalsmith from 'metalsmith'
import collections from '@metalsmith/collections'
import layouts from '@metalsmith/layouts'
import markdown from '@metalsmith/markdown'
import permalinks from '@metalsmith/permalinks'
import drafts from '@metalsmith/drafts'

const __dirname = dirname(fileURLToPath(import.meta.url))
const t1 = performance.now()
const devMode = process.env.NODE_ENV === 'development'

Metalsmith(__dirname) // parent directory of this file
  .source('./src') // source directory
  .destination('./build') // destination directory
  .clean(true) // clean destination before
  .env({
    // pass NODE_ENV & other environment variables
    DEBUG: process.env.DEBUG,
    NODE_ENV: process.env.NODE_ENV
  })
  .metadata({
    // add any variable you want & use them in layout-files
    sitename: 'My Static Site & Blog',
    siteurl: 'https://example.com/',
    description: "It's about saying »Hello« to the world.",
    generatorname: 'Metalsmith',
    generatorurl: 'https://metalsmith.io/'
  })
  .use(drafts(devMode)) // only include drafts when NODE_ENV === 'development'
  .use(
    collections({
      // group all blog posts by adding key
      posts: 'posts/*.md' // collections:'posts' to metalsmith.metadata()
    })
  ) // use `collections.posts` in layouts
  .use(
    markdown({
      // transpile all md file contents into html
      keys: ['description'], // and also file.description
      globalRefs: {
        // define links available to all markdown files
        home: 'https://example.com'
      }
    })
  )
  .use(permalinks()) // change URLs to permalink URLs
  .use(
    layouts({
      // wrap layouts around html
      pattern: '**/*.html'
    })
  )
  .build((err) => {
    // build process
    if (err) throw err // error handling is required
    console.log(`Build success in ${((performance.now() - t1) / 1000).toFixed(1)}s`)
  })

How does it work?

Metalsmith works in three simple steps:

1. Read all the files in a source directory.
2. Invoke a series of plugins that manipulate the files.
3. Write the results to a destination directory!

Each plugin is invoked with the contents of the source directory, and each file can contain YAML front-matter that will be attached as metadata, so a simple file like...

---
title: A Catchy Title
date: 2024-01-01
---
An informative article.

...would be parsed into...

{
  'path/to/my-file.md': {
    title: 'A Catchy Title',
    date: new Date(2024, 1, 1),
    contents: Buffer.from('An informative article'),
    stats: fs.Stats
  }
}

...which any of the plugins can then manipulate however they want. Writing plugins is incredibly simple, just take a look at the example drafts plugin.

Of course they can get a lot more complicated too. That's what makes Metalsmith powerful; the plugins can do anything you want!

Plugins

A Metalsmith plugin is a function that is passed the file list, the metalsmith instance, and a done callback. It is often wrapped in a plugin initializer that accepts configuration options.

Check out the official plugin registry at: https://metalsmith.io/plugins.
Find all the core plugins at: https://github.com/search?q=org%3Ametalsmith+metalsmith-plugin
See the draft plugin for a simple plugin example.

API

Check out the full API reference at: https://metalsmith.io/api.

CLI

In addition to a simple Javascript API, the Metalsmith CLI can read configuration from a metalsmith.json file, so that you can build static-site generators similar to Jekyll or Hexo easily. The example blog above would be configured like this:

metalsmith.json

{
  "source": "src",
  "destination": "build",
  "clean": true,
  "metadata": {
    "sitename": "My Static Site & Blog",
    "siteurl": "https://example.com/",
    "description": "It's about saying »Hello« to the world.",
    "generatorname": "Metalsmith",
    "generatorurl": "https://metalsmith.io/"
  },
  "plugins": [
    { "@metalsmith/drafts": true },
    { "@metalsmith/collections": { "posts": "posts/*.md" } },
    { "@metalsmith/markdown": true },
    { "@metalsmith/permalinks": "posts/:title" },
    { "@metalsmith/layouts": true }
  ]
}

Then run:

metalsmith

# Metalsmith · reading configuration from: /path/to/metalsmith.json
# Metalsmith · successfully built to: /path/to/build

Options recognised by metalsmith.json are source, destination, concurrency, metadata, clean and frontmatter. Checkout the static site, Jekyll examples to see the CLI in action.

Local plugins

If you want to use a custom plugin, but feel like it's too domain-specific to be published to the world, you can include plugins as local npm modules: (simply use a relative path from your root directory)

{
  "plugins": [{ "./lib/metalsmith/plugin.js": true }]
}

The secret...

We often refer to Metalsmith as a "static site generator", but it's a lot more than that. Since everything is a plugin, the core library is just an abstraction for manipulating a directory of files.

Which means you could just as easily use it to make...

• A project scaffolder.
• A build tool for Sass files.
• A simple static site generator.
• A Jekyll-like static site generator.

Resources

• Gitter Matrix community chat for chat, questions
• X (formerly Twitter) announcements and the metalsmith.io news page for updates
• Awesome Metalsmith - great collection of resources, examples, and tutorials
• emmer.dev on metalsmith - A good collection of various how to's for metalsmith
• glinka.co on metalsmith - Another great collection of advanced approaches for developing metalsmith
• Getting to Know Metalsmith - a great series about how to use Metalsmith for your static site.

Troubleshooting

Set metalsmith.env('DEBUG', '*metalsmith*') to debug your build. This will log debug logs for all plugins using the built-in metalsmith.debug debugger. For older plugins using debug directly, run your build with export DEBUG=metalsmith-*,@metalsmith/* (Linux) or set DEBUG=metalsmith-*,@metalsmith/* for Windows.

Node Version Requirements

Future Metalsmith releases will at least support the oldest supported Node LTS versions.

Metalsmith 2.6.x supports NodeJS versions 14.18.0 and higher.
Metalsmith 2.5.x supports NodeJS versions 12 and higher.
Metalsmith 2.4.x supports NodeJS versions 8 and higher.
Metalsmith 2.3.0 and below support NodeJS versions all the way back to 0.12.

Compatibility & support policy

Metalsmith is supported on all common operating systems (Windows, Linux, Mac). Metalsmith releases adhere to semver (semantic versioning) with 2 minor gray-area exceptions for what could be considered breaking changes:

• Major Node version support for EOL (End of Life) versions can be dropped in minor releases
• If a change represents a major improvement that is backwards-compatible with 99% of use cases (not considering outdated plugins), they will be considered eligible for inclusion in minor version updates.

Credits

Special thanks to Ian Storm Taylor, Andrew Meyer, Dominic Barnes, Andrew Goodricke, Ismay Wolff, Kevin Van Lierde and others for their contributions!

License

headings's Issues

Tests always pass

Please correct me if I'm wrong, but it seems the test cases provided will never fail.
This is because you're calling the done() callback with any errors, thus suppressing a possible failed test case.

For example, the following test passes:

it('should preserve order with multiple selectors', function(done){
    Metalsmith('test/fixture')
      .use(markdown())
      .use(headings({ selectors: ['h1', 'h2']}))
      .build(function(err, files){
        if (err) return done(err);
        expect(1).toEqual(2)
        done();
      });
  });

I'd suggest just letting any error through.

examples of how to use are welcome

It is not obvious to understand how to use this plugin on the template side.

At least, a simple example in the README file would be welcome.

Test Cases Use Markdown instead of HTML

This plugin is supposed to run after markdown has been run on the input. However, all of the src data in the test/fixture directory are .md files.

Shouldn't they be .html files?

generate multi-level menus

There are many examples on the web on how to generate multi-level menus with handlebars. The problem is that they are often based on the following data structure :

var headings = [
    { id: "foo1", tag: "h1", text: "foo1 text", items: [
        { id: "foo11", tag: "h2", text: "foo11 text" },
        { id: "foo12", tag: "h2", text: "foo12 text" }
    ]},
    { id: "foo2", tag: "h1", text: "foo2 text" },
    { id: "foo3", tag: "h1", text: "foo3 text" }
];

As you can see, submenus are embedded in their parent menu.

metalsmith-headings generates a flat data structure :

var headings = [
    { id: "foo1", tag: "h1", text: "foo1 text" },
    { id: "foo11", tag: "h2", text: "foo11 text" },
    { id: "foo12", tag: "h2", text: "foo12 text" },
    { id: "foo2", tag: "h1", text: "foo2 text" },
    { id: "foo3", tag: "h1", text: "foo3 text" }
];

It is then harder to generate a correct menu with handlebars.

I'd like to get something like this in html :

<!-- toc -->
<div class="col-md-3">
    <div class="sidebar hidden-print affix-top toc" role="complementary">
        <ul class="nav sidenav">
            <li ><a href="#foo1">foo1 text</a>
                <ul class="nav">
                    <li class=""><a href="#foo11">foo11 text</a></li>
                    <li class=""><a href="#foo12">foo12 text</a></li>
                </ul>
            </li>
            <li><a href="#foo2">foo2 text</a></li>
            <li><a href="#foo3">foo3 text</a></li>
        </ul>
    </div>
</div>

As you can see, sublist ul is embedded in its parent li.

I manage to start something that works a little bit. But there is large flaws to improve. I'm not an expert in js, nor in handlebars. You can see a working test the following JSFiddle example.

Mains flaws are :

• I'm not sure the generated html would be correct in any cases
• html is generated by helper whereas it should be generated by the template

Feel free to share your thinking, to improve my solution, and to discuss about the data structure that metalsmith-headers should generate.

merge hegemonic's pull request

Hey,

is there any chance you can merge in hegemonic's pull request? It seems, that the metalsmith-headings plugin requires this functionality to allow building multi level navs.