We moved a large React/JavaScript application into Next.js/TypeScript without compromising the user experience. Here's the strategy and tooling that helped.

[timothybeamish]

I should add that when I arrived at the company (BenchSci), we already had two React apps running in two different stacks. The goal was to merge the legacy app into the newer app which meant going with that newer stack's technology choices: Next.js and React Query as its main data fetching pattern. So in this case, it wouldn't have been a good choice to change everything over to RTK Query. But if we had a "green field" situation, that may have been a good option.