Pyodide

The Python scientific stack, compiled to WebAssembly.

It provides transparent conversion of objects between Javascript and Python. When inside a browser, this means Python has full access to the Web APIs.

While closely related to the iodide project, Pyodide may be used standalone in any context where you want to run Python inside a web browser.

For more information, see the demo and the documentation.

Building

Building is easiest on Linux. For other platforms, we recommend using the Docker image (described below) to build Pyodide.

Make sure the prerequisites for emsdk are installed. Pyodide will build a custom, patched version of emsdk, so there is no need to build it yourself prior.

Additional build prerequisites are:

• A working native compiler toolchain, enough to build CPython.
• A native Python 3.7 to run the build scripts.
• PyYAML
• lessc to compile less to css.
• uglifyjs to minify Javascript builds.
• ccache (optional) recommended for much faster rebuilds.

make

Using Docker

We provide a Debian-based Docker image on Docker Hub with the dependencies already installed to make it easier to build Pyodide.

1. Install Docker

2. From a git checkout of Pyodide, run ./run_docker

3. cd /src

4. Run make to build.

You can edit the files in your source checkout on your host machine, and then repeatedly run make inside the Docker environment to test your changes.

Testing

Install the following dependencies into the default Python installation:

pip install pytest selenium pytest-instafail

Install geckodriver and chromedriver somewhere on your PATH.

pytest test/

Benchmarking

Install the same dependencies as for testing.

make benchmark

Linting

Python is linted with flake8. C and Javascript are linted with clang-format.

make lint