First install Rust if not already done:

curl https://sh.rustup.rs -sSf | sh

(More details here if you are not using Linux.)

To build the WASM and Javascript files, you need to install wasm-bindgen in addition to the nightly version of Rust:

rustup target add wasm32-unknown-unknown --toolchain nightly
cargo +nightly install wasm-bindgen-cli

To test the demo page, you have to load the WASM/Javascript files from an HTTP server. To start a local HTTP server, you can use (requires python):

# For python 2
python -m SimpleHTTPServer
# For python 3
python -m http.server

Then load in your favourite browser the URL http://localhost:8000/test.html and/or http://localhost:8000/demo.html