DanMage is a project that brings NicoNico-style flow chat (A.K.A., scrolling chat, danmaku, danmu) to multiple video sites as both a chrome extension and a firefox extension, now supporting YouTube, Twitch and Crunchyroll. It's also deployed as a website, which provides minimum backend support to the extension, such as storing posted chats and player settings.
To build the chrome extension, run npm run bext which dumps the bundled JS files into ./chrome_extension_bin directory, which can be loaded in debug mode in browsers. It talks directly to the PROD web server.
To build the firefox extension, run npm run bext_firefox_windows or npm run bext_firefox_linux depending on your OS. The only extra thing it does than npm run bext is to copy and rename firefox_manifest.json in ./chrome_extension_bin directory.
To run the web server locally, run npm run local which starts at port 8080.
It's deployed to Google Cloud Platform (GCP) by using Google Cloud Build which requires cloudbuild.yaml and Dockerfile.