So Blazor server is in production with Core 3.0 and web assembly is in preview until Core 3.1 - according to Microsoft.
When I want to create Blazor app with Visual Studio 2019 16.3.1 I can choose between
Can someone confirm if WebAssembly App is fully functional and can be used for production or I am misinterpreting something here?
Blazor WebAssembly is in Preview and Microsoft do not currently support it for production use. It's due for release around May 2020, which is when production support will begin, or close to then.
That said whether you use it in production or not comes down to your judgement. For example my team have been building apps with it since early this year and we're getting on great. But only you can make that call for your project.
But to be clear Microsoft do not currently support production scenarios with Blazor WebAssembly.
A lot has changed through the various previews of Blazor. Last week I tried to go through the one Blazor course on Lynda.com, which was based on much earlier prerelease versions of Blazor. I was using the latest Blazor, , and, because of the many breaking changes, it was a fool's errand and wasted a lot of time. Changes in namespaces, changes in method names, resulted in many build errors, and then I would Google for those errors, which usually led to answers like "Update to the newest Blazor Preview". I finally bailed on the effort to update the sample app's code as a waste of time.
For an example of one set of breaking changes, and fixes required, search YouTube for a video named, "Blazor Preview 8 Template Fix - Fixing the Breaking Changes" by IAmTimCorey.
So, can you use PreRelease Blazor WebAssembly for production? It could be OK in a very limited scenario, if you have a very small number of users, and excellent communication with them. However, I suspect the "final" "production" version of WebAssembly, estimated for May 2020, is likely to have some additional breaking changes. Do you have time and resources to update the application to the production-version of Blazor Webassembly? Including retesting? Now, you could get lucky and have very few or no changes. We are getting closer and closer to the expected official production release date for WebAssembly.
Personally, for any Blazor app built with prerelease WebAssembly, I would advertise it to the customer as being "Prerelease", and not to be relied on for mission-critical business functions, and only suitable for limited use. I do think it could be suitable for (very) "limited production use" with key customer staff, to get their feedback on what works well and what needs changes (e.g., UI issues, performance issues), as a Lean Startup "MVP" type of offering.
