Example for the wasm bindings from https://github.com/iotaledger/identity.rs
Install the dependencies...
npm i
...then start Rollup:
npm run dev
Navigate to localhost:5000. You should see your app running. Edit a component file in src, save it, and reload the page to see your changes.
To create an optimised version of the app:
npm run build
You can run the newly built app with npm run start. This uses sirv, which is included in your package.json's dependencies so that the app will work when you deploy to platforms like Heroku.