@downey An example I've dealt with was an ASP .NET Blazor website, which requires webassembly for basic loading of the page. At the time I started the project, we had a significant number of users still on Internet Explorer, so I added a javascript file to the root page that detects if webassembly is missing and shows a popup suggesting to open Edge. That prevented me from needing to maintain a list of browsers which either do or don't support it, and I could just let the browser tell me itself.