@enmo-design/html2pdf

html2pdf

html2pdf converts any webpage or element into a printable PDF entirely client-side using html2canvas and jsPDF.

Getting started

HTML

The simplest way to use html2pdf is to download dist/html2pdf.bundle.min.js to your project folder and include it in your HTML with:

<script src="html2pdf.bundle.min.js"></script>

NPM

Install html2pdf and its dependencies using NPM with npm install --save @enmo-design/html2pdf.

Note: You can use NPM to create your project, but html2pdf will not run in Node.js, it must be run in a browser.

Usage

Once installed, html2pdf is ready to use. The following command will generate a PDF of #element-to-print and prompt the user to save the result:

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

Advanced usage

Every step of html2pdf is configurable, using its new Promise-based API. If html2pdf is called without arguments, it will return a Worker object:

var worker = html2pdf();  // Or:  var 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 canvas and PDF objects before saving.
var worker = html2pdf().from(element).save();

Workflow

The basic workflow of html2pdf tasks (enforced by the prereq system) is:

.from() -> .toContainer() -> .toCanvas() -> .toImg() -> .toPdf() -> .save()

Worker API

Method	Arguments	Description
from	src, type	Sets the source (HTML string or element) for the PDF. Optional type specifies other sources: 'string', 'element', 'canvas', or 'img'.
to	target	Converts the source to the specified target ('container', 'canvas', 'img', or 'pdf'). Each target also has its own toX method that can be called directly: toContainer(), toCanvas(), toImg(), and toPdf().
output	type, options, src	Routes to the appropriate outputPdf or outputImg method based on specified src ('pdf' (default) or 'img').
outputPdf	type, options	Sends type and options to the jsPDF object's output method, and returns the result as a Promise (use .then to access). See the jsPDF source code for more info.
outputImg	type, options	Returns the specified data type for the image as a Promise (use .then to access). Supported types: 'img', 'datauristring'/'dataurlstring', and 'datauri'/'dataurl'.
save	filename	Saves the PDF object with the optional filename (creates user download prompt).
set	opt	Sets the specified properties. See Options below for more details.
get	key, cbk	Returns the property specified in key, either as a Promise (use .then to access), or by calling cbk if provided.
then	onFulfilled, onRejected	Standard Promise method, with this re-bound to the Worker, and with added progress-tracking (see Progress below). Note that .then returns a Worker, which is a subclass of Promise.
thenCore	onFulFilled, onRejected	Standard Promise method, with this re-bound to the Worker (no progress-tracking). Note that .thenCore returns a Worker, which is a subclass of Promise.
thenExternal	onFulfilled, onRejected	True Promise method. Using this 'exits' the Worker chain - you will not be able to continue chaining Worker methods after .thenExternal.
catch, catchExternal	onRejected	Standard Promise method. catchExternal exits the Worker chain - you will not be able to continue chaining Worker methods after .catchExternal.
error	msg	Throws an error in the Worker's Promise chain.

A few aliases are also provided for convenience:

Method	Alias
save	saveAs
set	using
output	export
then	run

Options

html2pdf can be configured using an optional opt parameter:

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

// 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:

Name	Type	Default	Description
margin	number or array	0	PDF margin (in jsPDF units). Can be a single number, [vMargin, hMargin], or [top, left, bottom, right].
filename	string	'file.pdf'	The default filename of the exported PDF.
pagebreak	object	{mode: ['css', 'legacy']}	Controls the pagebreak behaviour on the page. See Page-breaks below.
image	object	{type: 'jpeg', quality: 0.95}	The image type and quality used to generate the PDF. See Image type and quality below.
enableLinks	boolean	true	If enabled, PDF hyperlinks are automatically added ontop of all anchor tags.
html2canvas	object	{ }	Configuration options sent directly to html2canvas (see here for usage).
jsPDF	object	{ }	Configuration options sent directly to jsPDF (see here for usage).

Page-breaks

html2pdf 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, html2pdf 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

Setting	Type	Default	Description
mode	string or array	['css', 'legacy']	The mode(s) on which to automatically add page-breaks. One or more of 'avoid-all', 'css', and 'legacy'.
before	string or array	[]	CSS selectors for which to add page-breaks before each element. Can be a specific element with an ID ('#myID'), all elements of a type (e.g. 'img'), all of a class ('.myClass'), or even '*' to match every element.
after	string or array	[]	Like 'before', but adds a page-break immediately after the element.
avoid	string or array	[]	Like 'before', but avoids page-breaks on these elements. You can enable this feature on every element using the 'avoid-all' mode.

Page-break modes

Mode	Description
avoid-all	Automatically adds page-breaks to avoid splitting any elements across pages.
css	Adds page-breaks according to the CSS break-before, break-after, and break-inside properties. Only recognizes always/left/right for before/after, and avoid for inside.
legacy	Adds page-breaks after elements with class html2pdf__page-break. This feature may be removed in the future.

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'] }
});

// 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:

Name	Type	Default	Description
type	string	'jpeg'	The image type. HTMLCanvasElement only supports 'png', 'jpeg', and 'webp' (on Chrome).
quality	number	0.95	The image quality, from 0 to 1. This setting is only used for jpeg/webp (not png).

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. It will be updated to allow a progress callback that will be called with each update, however it is currently a work-in-progress.

Contributing

Contributors

• @node-rookie

License

The MIT License