The main branch is already using emscripten >=4.x and the experimental channel https://prefix.dev/channels/emscripten-forge-4x. The old emscripten 3.1.73 based branch is available at https://github.com/emscripten-forge/pyjs/tree/emscripten-3.1.73

pyjs is modern pybind11 + emscripten Embind based Python <-> JavaScript foreign function interface (FFI) for wasm/emscripten compiled Python.

The API is loosly based on the FFI of pyodide.

See the documentation for a full documentation.

• To try it out, you can use the playground.
• To create your own jupyterlite deployments use xeus-lite-demo

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