PDF.js

PDF.js is a Portable Document Format (PDF) viewer that is built with HTML5.

PDF.js is community-driven and supported by Mozilla. Our goal is to create a general-purpose, web standards-based platform for parsing and rendering PDFs.

Contributing

PDF.js is an open source project and always looking for more contributors. To get involved, visit:

• Issue Reporting Guide
• Code Contribution Guide
• Frequently Asked Questions
• Good Beginner Bugs
• Projects

Feel free to stop by our Matrix room for questions or guidance.

Getting Started

Online demo

Please note that the "Modern browsers" version assumes native support for the latest JavaScript features; please also see this wiki page.

• Modern browsers: https://mozilla.github.io/pdf.js/web/viewer.html

• Older browsers: https://mozilla.github.io/pdf.js/legacy/web/viewer.html

Browser Extensions

Firefox

PDF.js is built into version 19+ of Firefox.

Chrome

• The official extension for Chrome can be installed from the Chrome Web Store. This extension is maintained by @Rob--W.
• Build Your Own - Get the code as explained below and issue npx gulp chromium. Then open Chrome, go to Tools > Extension and load the (unpackaged) extension from the directory build/chromium.

PDF debugger

Browse the internal structure of a PDF document with https://mozilla.github.io/pdf.js/internal-viewer/web/debugger.html

Getting the Code

To get a local copy of the current code, clone it using git:

$ git clone https://github.com/mozilla/pdf.js.git
$ cd pdf.js

Next, install Node.js via the official package or via nvm. If everything worked out, install all dependencies for PDF.js:

$ npm install

Finally, you need to start a local web server as some browsers do not allow opening PDF files using a file:// URL. Run:

$ npx gulp server

and then you can open:

• http://localhost:8888/web/viewer.html

Please keep in mind that this assumes the latest version of Mozilla Firefox; refer to Building PDF.js for non-development usage of the PDF.js library.

It is also possible to view all test PDF files on the right side by opening:

• http://localhost:8888/test/pdfs/?frame

Building PDF.js

In order to bundle all src/ files into two production scripts and build the generic viewer, run:

$ npx gulp generic

If you need to support older browsers, run:

$ npx gulp generic-legacy

This will generate pdf.js and pdf.worker.js in the build/generic/build/ directory (respectively build/generic-legacy/build/). Both scripts are needed but only pdf.js needs to be included since pdf.worker.js will be loaded by pdf.js. The PDF.js files are large and should be minified for production.

Code coverage

We track how much of the code is exercised by the test suite on Codecov (see the badge at the top of this file).

How it is collected

When coverage is enabled, the build instruments the bundled code with babel-plugin-istanbul, which adds counters that record every line, branch and function that runs:

• For browser-based tests (unit, integration and reference tests) the instrumented code runs in the browser, fills a global window.__coverage__ object, and the test runner collects it from each browser session, merges the results, and writes the report.
• For the Node-based unit tests (unittestcli) the raw data is written to build/tmp/unittestcli-coverage.json and turned into a report afterwards.

Collecting coverage locally

Add the --coverage flag to any of the test tasks, for example:

$ npx gulp unittest --coverage           # browser unit tests
$ npx gulp unittestcli --coverage        # Node unit tests
$ npx gulp integrationtest --coverage    # Puppeteer integration tests
$ npx gulp botbrowsertest --coverage     # reference tests

The following options control the output:

Option	Description	Default
--coverage	Enable coverage collection.	off
--coverage-output <dir>	Directory where the report is written.	build/coverage
--coverage-formats <list>	Comma-separated list of formats: info, html, json, text, cobertura, clover.	info
--coverage-per-test	Also build a per-test index (see below).	off

By default the report is written to build/coverage in the info format, i.e. an LCOV lcov.info file (the same format that is uploaded to Codecov). Use --coverage-formats html to get a browsable HTML report instead, or pass several formats at once, e.g. --coverage-formats info,html.

Finding which tests cover a given line

coverage_search lists the ref tests that exercised a specific source line or function. It uses the per-test index (per-test-index.json) that is rebuilt on every push to master and published to the pdf.js.refs repository. The index is downloaded on demand, cached locally, and only re-downloaded when it has changed, so no local coverage build is required:

$ npx gulp coverage_search --code="canvas.js::205"
$ npx gulp coverage_search --code="canvas.js::drawImageAtIntegerCoords"

To run — or regenerate the reference images for — only the ref tests that touch a given line or function, pass the same --code option to a browser test or makeref task:

$ npx gulp browsertest --code="canvas.js::205"
$ npx gulp makeref --code="canvas.js::205"

Pass --no-download to reuse the locally cached index without contacting the network. The index can also be built and queried locally (the CI job that publishes it builds it the same way):

$ npx gulp botbrowsertest --coverage-per-test
$ npx gulp coverage_search --code="canvas.js::205" \
    --index=build/coverage/per-test-index.json --no-download

Continuous integration

On every push and pull request three GitHub Actions workflows collect coverage and upload it to Codecov, each tagged with its own Codecov flag so the test types can be told apart:

Workflow	Task	Codecov flag
unit_tests.yml	unittest	unittest
integration_tests.yml	integrationtest	integrationtest
coverage_browser_tests.yml	botbrowsertest	browsertest

Using PDF.js in a web application

To use PDF.js in a web application you can choose to use a pre-built version of the library or to build it from source. We supply pre-built versions for usage with NPM under the pdfjs-dist name. For more information and examples please refer to the wiki page on this subject.

Including via a CDN

PDF.js is hosted on several free CDNs:

• https://www.jsdelivr.com/package/npm/pdfjs-dist
• https://cdnjs.com/libraries/pdf.js
• https://unpkg.com/pdfjs-dist/

Learning

You can play with the PDF.js API directly from your browser using the live demos below:

• Interactive examples

More examples can be found in the examples folder. Some of them are using the pdfjs-dist package, which can be built and installed in this repo directory via npx gulp dist-install command.

For an introduction to the PDF.js code, check out the presentation by our contributor Julian Viereck:

• https://www.youtube.com/watch?v=Iv15UY-4Fg8

More learning resources can be found at:

• https://github.com/mozilla/pdf.js/wiki/Additional-Learning-Resources

The API documentation can be found at:

• https://mozilla.github.io/pdf.js/api/

Questions

Check out our FAQs and get answers to common questions:

• https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions

Talk to us on Matrix:

• https://chat.mozilla.org/#/room/#pdfjs:mozilla.org

File an issue:

• https://github.com/mozilla/pdf.js/issues/new/choose