This is a project template for Svelte apps. It lives at https://github.com/vrde/svelte-web-extension-template.
To create a new project based on this template using degit:
npx degit vrde/svelte-web-extension-template my-web-extension
cd my-web-extension
Note that you will need to have Node.js installed.
Install the dependencies...
cd my-web-extension
npm install
...then start Rollup:
npm start
This starts a new session of Chromium and loads the extension temporary in the browser.
To start Firefox, run:
npm run start:firefox