Nodepub v3.0.2

Create valid EPUB 2 ebooks with metadata, contents, and cover image.

About Nodepub

Nodepub is a Node module which can be used to create EPUB 2 documents.

• Files pass the IDPF online validator
• Files meet Sigil's preflight checks
• Files open fine in iBooks, Adobe Digital Editions, and Calibre
• Files open fine with the Kobo H20 ereader
• Files are fine as KindleGen input
• PNG/JPG cover images - recommend 600x800, 600x900, or similar as minimum
• Custom CSS can be provided
• Inline images within the EPUB
• Optionally generate your own contents page
• Front matter before the contents page
• Exclude sections from auto contents page and metadata-based navigation
• OEBPS and other 'expected' subfolders within the EPUB

Development is done against Node v15.6.0 since v3.0.0 (February 2021). Node v10.3 or later should work fine.

Breaking changes over v2

• In v2 the cover image was specified as a parameter when the document is first constructed

  • In v3 that parameter is removed and becomes a cover metadata entry instead
  • As a bonus, cover images should now work for jpg and gif as well as png

• It now uses async/await and so requires newer versions of Node

  • Public methods are therefore called slightly differently
  • The actual content of generated EPUBs remains the same

• You can view the change log here.

• Developers of Nodepub itself can see some helpful information here.

Installing Nodepub

It's on npm at https://www.npmjs.com/package/nodepub. Add it as with any other module:

npm i nodepub

Then import it for use:

var nodepub = require("nodepub");

Defining your EPUB

• Documents consist of metadata and sections
  • Metadata is an object with various properties detailing the book
  • Sections are chunks of HTML that can be thought of as chapters

Here's some sample metadata:

var metadata = {
  id: '278-123456789',
  cover: '../test/cover.jpg',
  title: 'Unnamed Document',
  series: 'My Series',
  sequence: 1,
  author: 'KA Cartlidge',
  fileAs: 'Cartlidge,KA',
  genre: 'Non-Fiction',
  tags: 'Sample,Example,Test',
  copyright: 'Anonymous, 1980',
  publisher: 'My Fake Publisher',
  published: '2000-12-31',
  language: 'en',
  description: 'A test book.',
  contents: 'Table of Contents',
  source: 'http://www.kcartlidge.com',
  images: ["../test/hat.png"]
};

• The cover should be an image as described in the bullet points at the top of this document
• The series and sequence are not recognised by many readers (the Calibre properties are used)
• The tags become subjects in the final EPUB
• For published note the year-month-day format
• The language is the short ISO language name (en, fr, de etc)
• The images array is where you refer to all images used inside the book. Within your section HTML you always link to one all-containing flat folder: <img src="../images/hat.png" />

Call the document method with the aforementioned metadata object detailing your book (previous versions needed the path of a cover image as a call parameter; this is no longer the case as it is now part of the metadata itself).

var epub = nodepub.document(metadata);

Fill in the content

The bulk of the work is adding your content.

Call addSection with a title and the HTML contents for each section (usually a chapter), plus options for whether to exclude it from the contents page list and/or to use it as front matter.

epub.addSection('Copyright', copyright, false, true);
epub.addSection('Chapter 1', "<h1>One</h1><p>...</p>");

Excluding from the contents page list allows you to add content which does not appear either in the auto-generated HTML table of contents or the metadata contents used directly by ereaders/software. This is handy for example when adding a page at the end of the book with details of your other books - a common page which may not appear in the book contents.

Flagging as front matter still includes it but passes that flag into any custom content page generation function you may choose to provide. Front matter will also appear in your book ahead of the contents page when read linearly. Useful for dedication pages, for example.

Optionally add some extra CSS

You can inject basic CSS into your book.

epub.addCSS(`p { text-indent: 0; } p+p { text-indent: 0.75em; }`);

You can also choose to make your own custom contents page

A standard contents page is included automatically, but can be overridden.

You can create your own by passing a second parameter when creating a document - a function which is called when the contents page is being constructed. That function will be given details of all the links, and is expected to return HTML to use for the contents page.

var makeContentsPage = (links) => {
  var contents = "<h1>Chapters</h1>";
  links.forEach((link) => {
    if (link.itemType !== "contents") {
      contents += "<a href='" + link.link + "'>" + link.title + "</a><br />";
    }
  });
  return contents;
};
var epub = nodepub.document(metadata, makeContentsPage);

The links array which is passed to your callback function consists of objects with the following properties:

• title - the title of the section being linked to
• link - the relative href within the EPUB
• itemType - one of 3 types, those being front for front matter, contents for the contents page, and main for the remaining sections
  • You can use this to omit front matter from the contents page if required

Your callback function should return a string of HTML which will form the body of the contents page. The example.js mentioned in the next section shows this in action.

Generating your EPUB

Note that Nodepub is asynchronous, actionable using async/await.

// DEFAULT: Using Nodepub when your code IS asynchronous.
await epub.writeEPUB('/folder', 'filename-without-extention');

// EDGE CASE: Using Nodepub when your code IS NOT asynchronous.
(async () => {
  try {
    await epub.writeEPUB('example', 'example');
  } catch (e) {
    console.log(e);
  }
})();

For a full example, see example.js, which uses Nodepub from synchronous code.

Option 1 - Creating a complete EPUB file ready for distribution

This is the simplest option.

await epub.writeEPUB('/folder', 'filename-without-extention');

Option 2 - Creating a folder containing all the files necessary to build the final EPUB yourself

If you need to do further work on your EPUB, this option writes the entire constituent files into a folder. When you create your EPUB it should consist of this folder's contents zipped up and renamed, with the sole proviso that the first file in the zip should be the mimetype file (stored, not compressed).

await epub.writeFilesForEPUB('/folder-for-constituent-files');

Option 3 - Creating a Javascript object containing all the filenames and content needed for the final EPUB

Finally, you can have the same set of content files returned to you directly for you to do what you want with (e.g. to store in a database).

const files = await epub.getFilesForEPUB();

This returns an array of objects, one per file, looking similar to the following:

const files = [{
  name: 'toc.xhtml', folder: 'OEBPF/content', compress: true, content: 'raw-content-to-write',
}];

The content may be HTML, plain text, or byte arrays for images. It is in a complete and final form. Writing these to a renamed zip file, honouring the compress flag, with mimetype first, gives an EPUB.

The full example

In the top folder (containing the package.json file) run the following.

npm run example

This will generate various outputs in the examplefolder.

Substitutions within your book content

A simple form of text substitution is supported. At any point in your section's content you may include placeholders like [[COPYRIGHT]]. When the EPUB is generated any such placeholders which match the capitalised name of a metadata entry are replaced with the corresponding metadata value.

For example, you could have a "Thanks for Reading" page at the end of your book which has the following markup:

<p>Thanks for reading <strong>[[TITLE]]</strong> by <em>[[AUTHOR]]</em>.</p>

When the EPUB is produced and opened, if your metadata was set as per the book "The Hobbit" by "JRR Tolkien", then it will look like this:

Thanks for reading The Hobbit by JRR Tolkien.

This means you can re-use content across multiple books, or refer to the author/title/series/whatever at any point within the book without worrying about consistency or maintenance.

Reminder

This is a utility module, not a user-facing one. In other words it is assumed that the caller has already validated the inputs. Only basic omission checks are performed.