Summary:
The author, who has experience in converting JavaScript applications to TypeScript, discusses two approaches to converting codebases: a relaxed approach and a more rigorous approach. The relaxed approach involves gradually converting files and enabling strictness flags as you go, while the rigorous approach focuses on converting modules in a “leaves-first” order and ensuring all dependencies have types. The author recommends the more rigorous approach due to the challenges and limitations of the relaxed approach. They highlight the importance of considering the size of the codebase and the benefits of a solid foundation of typed dependencies. Implementing the rigorous approach requires discipline and buy-in from stakeholders but results in a better experience for all.
https://v5.chriskrycho.com/journal/how-to-do-a-typescript-conversion/