wasm-demo

This is a simple demonstration of using WebAssembly (WASM).

Manually coding WebAssembly

See the files math.wat and wat.html.

To build and run this:

1. Install WebAssembly Binary Toolkit (WABT). This includes a set of command line tools including wat2wasm, wasm2wat, wasm-validate, and wasm-interp. In macOS this can be installed using Homebrew by entering brew install wabt.

2. Enter wat2wasm math.wat to create the binary file math.wasm from the text file math.wat.

3. Start a local HTTP file server. One approach is to install Deno and then enter these commands:

   deno install --allow-net --allow-read https://deno.land/std@0.87.0/http/file_server.ts
   file_server .

4. Browse localhost:{port}/wat.html where port is the port on which the local server is listening.

See this wat2wasm issue.

Converting Rust to WASM

See the files rust/Cargo.toml, rust/src/lib.rs and rust.html.

To build and run this:

1. Install wasm-pack by entering the following command:

   curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh

2. cd rust

3. Enter wasm-pack build --target web

4. Start a local HTTP file server as described earlier.

5. Browse localhost:{port}/rust.html where port is the port on which the local server is listening.

Running outside a web browser

WASM code can be run outside of a web browser. To try this:

1. Enter rustup target add wasm32-wasi.
2. Enter cargo new demo
3. Enter cd demo
4. Enter cargo build --target wasm32-wasi
5. Install the Wasmtime CLI by entering curl https://wasmtime.dev/install.sh -sSf | bash
6. Open a new terminal.
7. Run the program by entering wasmtime target/wasm32-wasi/debug/demo.wasm