pyjs#

pyjs is a Python ↔ JavaScript FFI for WebAssembly, built with pybind11 and emscripten’s embind. It lets you run Python in the browser (main thread or web worker) and use JavaScript from Python, and Python from JavaScript.

Quickstart#

Access JavaScript from Python:

import pyjs

# hello world
pyjs.js.console.log("Hello, World!")

# create a JavaScript function to add two numbers
js_function = pyjs.js.Function("a", "b", """
    console.log("Adding", a, "and", b)
    return a + b
""")

# call the function
result = js_function(1, 2)

Access Python from JavaScript:

// hello world
pyjs.eval("print('Hello, World!')")

// eval a python expression and get the result
const py_list = pyjs.eval("[i for i in range(10)]")

// access
console.log(py_list.get(0)) // same as py_list[0] on the python side

Try it out#

Use the Python REPL in these docs, the JavaScript API tour, or the full JupyterLite deployment.

User guide

API reference

Internals