GitHub - eKoopmans/html2pdf.js: Client-side HTML-to-PDF rendering using pure JS.
source link: https://github.com/eKoopmans/html2pdf.js
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README.md
html2pdf.js
html2pdf.js converts any webpage or element into a printable PDF entirely client-side using html2canvas and jsPDF.
Table of contents
Getting started
HTML
The simplest way to use html2pdf.js 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>
Note: Click here for more information about using the unbundled version dist/html2canvas.min.js
.
NPM
Install html2pdf.js and its dependencies using NPM with npm install --save html2pdf.js
(make sure to include .js
in the package name).
Note: You can use NPM to create your project, but html2pdf.js will not run in Node.js, it must be run in a browser.
Bower
Install html2pdf.js and its dependencies using Bower with bower install --save html2pdf.js
(make sure to include .js
in the package name).
Console
If you're on a webpage that you can't modify directly and wish to use html2pdf.js to capture a screenshot, you can follow these steps:
- Open your browser's console (instructions for different browsers here).
- Paste in this code:
function addScript(url) { var script = document.createElement('script'); script.type = 'application/javascript'; script.src = url; document.head.appendChild(script); } addScript('https://raw.githack.com/eKoopmans/html2pdf/master/dist/html2pdf.bundle.js');
- You may now execute html2pdf.js commands directly from the console. To capture a default PDF of the entire page, use
html2pdf(document.body)
.
Usage
Once installed, html2pdf.js 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.js is configurable, using its new Promise-based API. If html2pdf.js 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.js 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. Optionaltype
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 runOptions
html2pdf.js 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:
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.js 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.js 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 CSSbreak-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:
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.
Dependencies
html2pdf.js depends on the external packages html2canvas, jsPDF, and es6-promise. These dependencies are automatically loaded when using NPM or the bundled package.
If using the unbundled dist/html2pdf.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="es6-promise.auto.min.js"></script> <script src="jspdf.min.js"></script> <script src="html2canvas.min.js"></script> <script src="html2pdf.min.js"></script>
Contributing
Issues
When submitting an issue, please provide reproducible code that highlights the issue, preferably by creating a fork of this template jsFiddle (which has html2pdf.js already loaded). Remember that html2pdf.js uses html2canvas and jsPDF as dependencies, 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
-
Rendering: The rendering engine html2canvas isn't perfect (though it's pretty good!). If html2canvas isn't rendering your content correctly, I can't fix it.
- You can test this with something like this fiddle, to see if there's a problem in the canvas creation itself.
-
Node cloning (CSS etc): The way html2pdf.js clones your content before sending to html2canvas is buggy. A fix is currently being developed - try out:
- direct file: Go to html2pdf.js/bugfix/clone-nodes-BUILD and replace the files in your project with the relevant files (e.g.
dist/html2pdf.bundle.js
) - npm:
npm install eKoopmans/html2pdf.js#bugfix/clone-nodes-BUILD
- Related project: Bugfix: Cloned nodes
- direct file: Go to html2pdf.js/bugfix/clone-nodes-BUILD and replace the files in your project with the relevant files (e.g.
-
Resizing: Currently, html2pdf.js resizes the root element to fit onto a PDF page (causing internal content to "reflow").
- This is often desired behaviour, but not always.
- There are plans to add alternate behaviour (e.g. "shrink-to-page"), but nothing that's ready to test yet.
- Related project: Feature: Single-page PDFs
-
Rendered as image: html2pdf.js 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 currently unavoidable, however recent improvements in jsPDF mean that it may soon be possible to render straight into vector graphics.
- Related project: Feature: New renderer
-
Promise clashes: html2pdf.js relies on specific Promise behaviour, and can fail when used with custom Promise libraries.
- In the next release, Promises will be sandboxed in html2pdf.js to remove this issue.
- Related project: Bugfix: Sandboxed promises
-
Maximum size: HTML5 canvases have a maximum height/width. Anything larger will fail to render.
- This is a limitation of HTML5 itself, and results in large PDFs rendering completely blank in html2pdf.js.
- The jsPDF canvas renderer (mentioned in Known Issue #4) may be able to fix this issue!
- Related project: Bugfix: Maximum canvas size
Tests
html2pdf.js is currently sorely lacking in unit 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
Contributors
Special thanks
- Sauce Labs for unit testing.
License
Copyright (c) 2017-2019 Erik Koopmans <http://www.erik-koopmans.com/>
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