pyjs

Pyjs is C++ library, compiled to wasm, which allows to run Python code in the browser or in node. Pyjs is a loosly based on pyoide and comes with is a Javascript ⟺ Python foreign function interface so that you call these languages from each other. We would love to just use Pyodide’s FFI in emscripten forge, but it is very non-trivial to extract Pyodide’s FFI and use it for other projects. Therefore we created a modern Python - JavaScript FFI from scratch. This was done with the following tricks:

• Pybind11 is used to call Python from C++ and vice versa,

• Embind is used to call JavaScript from C++ and vice versa.

When we use Pybind11 and Embind together we can call Python from JavaScript and vice versa, with C++ as a man in the middle. This not only allows us to write a simple FFI from scratch with relatively little code but also avoids calling any low-level CPython APIs and enables using high-level constructs — like pybind11::object and emscripten::val — instead. The API is very similar to Pyodide’s so that it can be (allmost) be used as a drop-in replacement.