We are looking for a way to cope with AngularJS' LTS coming to its end. We have been working for about the last 3 years on a project, written using ASP.NET Core + AngularJS 1.5.7 + Fuse theme. Altogether we've invested about 10 development years into it. The alternatives we've looked at so far were migrating to Angular2+ or React, but we expect those alternatives to be too costly (we can't afford ourselves investing ~3 development years on such a migration project). We've also considered side-by-side development – that is leaving the current code as is, and using some more advanced technology only for new features – but we couldn't find a reasonable way to implement it, and it won't actually solve the main issue we have with the LTS ending. The main issue for us with AngularJS' LTS coming to its end is the lack of security updates that come as parts of new releases (and of course we are happy to advance to a newer technology regardless).
So which technology is the simplest to migrate to, and is there some tool or library that can help us?
React has a different mindset. React is about composition and state management. It's easier to build and compose components which for me speeds up the UI development. Plus, more features that aims for reusability and consistency of components and its state. Thus, I recommend React.
I've found myself in the same scenario 2 years ago, I did the migration to Angular and the difference between both versions is huge! you are basically going to create the project from zero (again). If that is the case, I recommend React. The learning curve is smaller, it's easy to develop and maintain, and it's way better when writing specs. You could work on the migration project in parallel doing releases per feature and then replace the project when the migration is done.
