HOW WE MIGRATED 160,000 LINES OF JAVASCRIPT TO TYPESCRIPT—WITH ZERO DOWNTIME

Summary from the TLDR Web Dev newsletter

WorkMade successfully migrated a 160,000-line JavaScript banking application to TypeScript with zero downtime over six weeks by using a separate migration branch, periodic rebasing, and incremental typing. It tested the TypeScript version in a staging environment with uptime monitoring and mirrored the production environment before pushing the changes to production.