html3pdf

html3pdf converts any webpage or element into a printable PDF entirely client-side using html2canvas and jsPDF.

This library is a continuation of, and is compatible with the API for, html2pdf.js by Erik Koopmans. The majority of this README was written by Erik Koopmans.

Differences from html2pdf.js:

Breaking changes:

• Dropped support for environments that don't have native Promises.
• Previously if you called the .toPdf() method of the html2pdf.js object, without explicitly calling .toCanvas() or .toImg(), the default worker object would have the properties .prop.canvas and .prop.img, which would be an HTMLCanvasElement and an HTMLImageElement respectively. Now the default types are Array\ and Array\. If you do not want them to be arrays, you can explicitly call .toCanvas() and .toImg(). See Workflow below for more details. This is a niche use case and if you don't know what any of this means, you probably don't need to worry about it.

Features/Bug fixes:

• Progress tracking API implemented.
• .toCanvases() and .toImgs() added to the worker API as alternatives to the original .toCanvas() and .toImg() methods. These are now the default if you simply call .toPdf() without being explicit about the rest of the chain. These functions create one canvas per page, and the corresponding images for each canvas. This resolves the issues with canvas size limits (unless each page is enormous).
• PRs from the original library merged: 170, 260, 261, 340, 447, 503, 516, 531, 569, 635, 641. These include: some fixes to the pagebreak calculations, the option to change what elements are used for pagebreaks and assign a class to those elements, the addition of the jsPDF documentProperties to the api, and a fix for the bug where long documents are blank - by rendering one canvas per page.

Table of contents

• Getting started
  • CDN
  • Raw JS
  • NPM
  • Bower
  • Console
• Usage
  • Advanced usage
  • Workflow
  • Worker API
• Options
  • Page-breaks
  • Page-break settings
  • Page-break modes
  • Example usage
  • Image type and quality
• Progress tracking
• Dependencies
• Contributing
  • Issues
  • Tests
  • Pull requests
• Credits
• License

Getting started

CDN

The simplest way to use html3pdf is to include it as a script in your HTML by using cdnjs:

<script src="https://github.com/davidnbooth/html3pdf.js/raw/merge_PRs/" integrity="" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

// TODO - add to CDN and add link here

Note: Read about dependencies for more information about using the unbundled version dist/html2canvas.min.js.

Raw JS

You may also download dist/html3pdf.bundle.min.js directly to your project folder and include it in your HTML with:

<script src="https://github.com/davidnbooth/html3pdf.js/raw/merge_PRs/html3pdf.bundle.min.js"></script>

NPM

Install html3pdf and its dependencies using NPM with npm install --save html3pdf

Note: You can use NPM to create your project, but html3pdf will not run in Node.js, it must be run in a browser.

Console

If you're on a webpage that you can't modify directly and wish to use html3pdf to capture a screenshot, you can follow these steps:

1. Open your browser's console (instructions for different browsers here).
2. Paste in this code:

   function addScript(url) {
       const script = document.createElement('script');
       script.type = 'application/javascript';
       script.src = url;
       document.head.appendChild(script);
   }
   addScript('');  // TODO add cdn link here

3. You may now execute html3pdf commands directly from the console. To capture a default PDF of the entire page, use html2pdf(document.body).

Usage

Once installed, html3pdf is ready to use. The following command will generate a PDF of #element-to-print and prompt the user to save the result:

const element = document.getElementById('element-to-print');
html2pdf(element);

Advanced usage

Every step of html3pdf is configurable, using a Promise-based API. If html3pdf is called without arguments, it will return a Worker object:

const worker = html2pdf();  // Or:  const worker = new html2pdf.Worker;

This worker has methods that can be chained sequentially, as each Promise resolves, and allows insertion of your own intermediate functions between steps. A prerequisite system allows you to skip over mandatory steps (like canvas creation) without any trouble:

// This will implicitly create the canvases and PDF objects before saving.
const worker = html2pdf().from(element).save();

Workflow

The basic workflow of html3pdf tasks (enforced by the prereq system) is:

// The default in html3pdf
.from() -> .toContainer() -> .toCanvases() -> .toImgs() -> .toPdf() -> .save()

// The default in html2pdf.js
.from() -> .toContainer() -> .toCanvas() -> .toImg() -> .toPdf() -> .save()

// You can also call .toImgs() after calling toCanvas(), it will just have an array with one image.
.from() -> .toContainer() -> .toCanvas() -> .toImgs() -> .toPdf() -> .save()

// But you can't call `.toImg` if you previously called `.toCanvases` on the same worker, `.toImg` does not want to assemble a single image out of multiple canvases.  If you need this for some reason, feel free to submit a PR!

Worker API

A few aliases are also provided for convenience:

Options

html3pdf can be configured using an optional opt parameter:

const element = document.getElementById('element-to-print');
const opt = {
  margin:             1,
  filename:           'myFile.pdf',
  image:              { type: 'jpeg', quality: 0.98 },
  html2canvas:        { scale: 2 },
  jsPDF:              { unit: 'in', format: 'letter', orientation: 'portrait' }
  documentProperties: { title: 'My PDF' }
};

// New Promise-based usage:
html2pdf().set(opt).from(element).save();

// Old monolithic-style usage:
html2pdf(element, opt);

The opt parameter has the following optional fields:

Page-breaks

html3pdf has the ability to automatically add page-breaks to clean up your document. Page-breaks can be added by CSS styles, set on individual elements using selectors, or avoided from breaking inside all elements (avoid-all mode).

By default, html3pdf will respect most CSS break-before, break-after, and break-inside rules, and also add page-breaks after any element with class html2pdf__page-break (for legacy purposes).

Page-break settings

Page-break modes

Example usage

// Avoid page-breaks on all elements, and add one before #page2el.
html2pdf().set({
  pagebreak: { mode: 'avoid-all', before: '#page2el' }
});

// Enable all 'modes', with no explicit elements.
html2pdf().set({
  pagebreak: { mode: ['avoid-all', 'css', 'legacy'], elementType: 'div', className: 'page_break' }  // you can change what kind of element is injected as a pagebreak, and add a class name to style those elements
});

// No modes, only explicit elements.
html2pdf().set({
  pagebreak: { before: '.beforeClass', after: ['#after1', '#after2'], avoid: 'img' }
});

Image type and quality

You may customize the image type and quality exported from the canvas by setting the image option. This must be an object with the following fields:

These options are limited to the available settings for HTMLCanvasElement.toDataURL(), which ignores quality settings for 'png' images. To enable png image compression, try using the canvas-png-compression shim, which should be an in-place solution to enable png compression via the quality option.

Progress tracking

The Worker object returned by html2pdf() has a built-in progress-tracking mechanism. Call the .listen() method at the end of your chain, e.g:

html2pdf().set(opt).from(element).save().listen(progressCallback);

The progressCallback should be a void function that accepts a single argument, which is this object:

 {
  val:    number   -  The current progress step.
  state:  string   -  A string describing the current step.
  n:      number   -  The number of total steps that will be completed.
  stack:  string[] -  The current stack of functions to be executed.
  ratio:  number   -  The current progress ratio. (val/n) -> Use this for progress bars!
 }

Dependencies

html3pdf depends on the external packages html2canvas, and jsPDF). These dependencies are automatically loaded when using NPM or the bundled package.

If using the unbundled dist/html3pdf.min.js (or its un-minified version), you must also include each dependency. Order is important, otherwise html2canvas will be overridden by jsPDF's own internal implementation:

<script src="https://github.com/davidnbooth/html3pdf.js/raw/merge_PRs/jspdf.min.js"></script>
<script src="https://github.com/davidnbooth/html3pdf.js/raw/merge_PRs/html3canvas.min.js"></script>
<script src="https://github.com/davidnbooth/html3pdf.js/raw/merge_PRs/html3pdf.min.js"></script>

Contributing

Issues

When submitting an issue, please remember that html3pdf is a wrapper around html2canvas and jsPDF, so it's a good idea to check each of those repositories' issue trackers to see if your problem has already been addressed.

Known issues

1. Rendering: The rendering engine html2canvas isn't perfect (though it's pretty good!). If html2canvas isn't rendering your content correctly, we can't fix it.

2. Node cloning (CSS etc): The way html3pdf clones your content before sending to html2canvas is buggy. A fix was being developed in html2pdf.js

3. Resizing: Currently, html3pdf resizes the root element to fit onto a PDF page (causing internal content to "reflow"). This is often desired behaviour, but not always.

4. Rendered as image: html3pdf renders all content into an image, then places that image into a PDF. This means text is not selectable or searchable, and causes large file sizes. This is the unavoidable reality of the html3pdf system of using html2canvas to render everything first. jsPDF may be used as the renderer in the future to avoid this.

Tests

Any contributions or suggestions of automated (or manual) tests are welcome. This is high on the to-do list for this project.

Pull requests

If you want to create a new feature or bugfix, please feel free to fork and submit a pull request! Create a fork, branch off of master, and make changes to the /src/ files (rather than directly to /dist/). You can test your changes by rebuilding with npm run build.

Credits

Erik Koopmans, html2pdf.js, and all other contributors to that project!

License

The MIT License

Copyright (c) 2017-2019 Erik Koopmans <http://www.erik-koopmans.com/>