python-in-browser

Running Python in the browser using Batavia and Starlette.

Demo

# frontend/app.py
import dom

print("Hello from Python!")

dom.document.title = "Hello world"
div = dom.document.getElementById("pyconsole")
div.innerHTML = div.innerHTML + "\n\nHello, World!\n\n"

raise ValueError("Just testing out exceptions!")

Installation

First, install Batavia. The full instructions are here, but we provide a convenience script that should work on Linux/macOS:

chmod +x scripts/install_batavia
./scripts/install_batavia

Then install Python dependencies:

python -m venv venv
. venv/bin/activate
pip install -r requirements.txt

You're good to go!

Quickstart

Start the web server:

uvicorn server:app

Go to http://127.0.0.1:8000, and the following will happen:

• An HTML page is shown. It was server-rendered via Jinja2 by the Starlette web app.
• The HTML page contains a script that contains the Python bytecode for frontend/app.py.
• The Batavia JS virtual machine is loaded and runs that bytecode.
• As a result, frontend/app.py ends up running in your browser, and doing stuff such as printing to the browser console and manipulating the DOM.

✨🌟✨