How We Migrated over 200K Lines of Code to TypeScript in 2 Days
5 min readApr 21, 2021
Background
CAT Tool
- Complex single-page application in production.
- Codebase created over 2 years ago (legacy code). People who architected and wrote a big part of the code don’t work here anymore.
- Still a lot of feature requests.
- More than 1300 files.
- Over 230K lines of code.
- Has Flow already but not everything was typed with Flow and Flow kind of sucks.
