[20kleagues]

This kind of behaviour (bridging js and native) is very common in apps in Asia - especially China. A lot of apps use html to render a lot of pages in their app to keep almost everything dynamic, but they also need to be able to use things like FaceID and sharing buttons from the native side on those html pages. They use a bridge similar to this to achieve this.

This is common enough in China that the term "H5" is used to refer to in-app html rendered pages via a webview which behave similar to a native screen through the use of these bridges.