At this stage RustPython only has preliminary support for web assembly. The instructions here are intended for developers or those wishing to run a toy example.

Using`rustup` add the compile target`wasm32-unknown-emscripten`. To do so you will need to have[rustup](https://rustup.rs/) installed.

To get started, install[wasm-bingden](https://rustwasm.github.io/wasm-bindgen/whirlwind-tour/basic-usage.html)

and[wasm-webpack](https://rustwasm.github.io/wasm-pack/installer/). You will also need to have`npm` installed.

source ./emsdk_env.sh

Move into the`wasm` directory. This contains a custombinary crate optimized fora web assembly build.

Move into the`wasm` directory. This contains a customlibrary crate optimized forwasm build of RustPython.

cd wasm

From here run the build. This can take several minutes depending on the machine.

Upon successful build, cd in the the`/pkg` directory and run:

Upon successful build,thefollowingfileswill be available:

Now move back out intothe`/app` directory. Thefileshere have been adapted from[wasm-pack-template](https://github.com/rustwasm/wasm-pack-template).

Finally, run:

-`rustpython_wasm.wasm`: the wasm build for rustpython. It includes both an parser and virtual machine.

-`rustpython_wasm.js`: the loading scripts for the above wasm file.

and you will be able to run the files with:

You will also find`index.html` in the`wasm` directory.

From here, you can copy these 3 files into the static assets directory of your web server and you should be

able to see the ouput in the web console of your browser.

Open a browser console and see the output of rustpython_wasm. To verify this, modify the line in`app/index.js`

rp.run_code("print('Hello Python!')\n");

To the following:

rp.run_code("assert(False)\n");

and you should observe:`Execution failed` in your console output, indicating that the execution of RustPython has failed.

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