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A port of the Processing visualization language to JavaScript.
Processing JavaScript HTML
Pull request Compare This branch is 164 commits ahead of jeresig:master.

Merge pull request #204 from DylanVann/master

Issue #203 : Added loadSketchFromSources callback.
latest commit 50ccecf274
@Pomax Pomax authored


For the project website, visit

This is the compilation repository for Processing.js, used in building the processing.js library from a series of Node.js flavoured commonjs modules, rather than existing as one large file as was the case in all versions up to and including 1.4.1 (released august 2012) .

The current version is 1.4.13 (released March 21, 2015)

note: this is not the repository for Processing, the language and IDE. Processing itself is hosted over at This is also not where to file bugs or ask questions about the "JS mode" that can be used with Processing, that project is hosted over at

Getting Processing.js

Bower install

bower install Processing.js

NPM install

npm install processing-js

Getting Processing.js the plain way

Simply grab the processing.js or processing.min.js files, include them as script on your webpage, and you're all set. See test.html for a simple example of using Processing.js on your pages.

Playing with the code

Clone this project using git, and ensure you have node.js installed. After cloning, install the require node packages using npm install in the processing-js directory. Modifying the code and building your own processing.js and processing.min.js files is then a fairly straight forward process. Modify the code as much as you want or need, then:

  1. Lint: $> grunt
  2. Test: $> node test

If step 1 gives you a "grunt: command not found" or similar error, run npm install -g grunt-cli to make sure grunt is globally installed as CLI command. If step 1 does not throw any errors, step 2 will run the Processing object through a battery of tests. Once the browser reference tests start, your processing.js and processing.min.js have been successfully built.

The test script also accepts the following optional arguments:

  • --test=testfile.pde runs one specific test
  • --nobuild does not build Pjs if all tests pass
  • --failonerror terminates the run if any error occurs.
  • --noref will not start a server process and a browser for doing ref testing.
  • --noautoref will start a server and a browser for ref testing, but doesn't auto-start the tests.

Manual operations

You can also perform the post-unit-test steps manually:

  • Build processing.js: $> browserify build.js -o processing.js
  • Minify processing.js: $> node minify
  • Run test server: $> node server

While the browser tests run

With the test server is running, the following urls are good to know:

Contributing to Processing.js

Please read "how to contribute to Processing.js" for how you can contribute, and what code of conduct is expected to be followed.

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