Ably, a cloud infrastructure and API provider for realtime messaging, recently migrated its main project from JavaScript to TypeScript. The motivation behind this migration was the need for a more strongly typed language to overcome challenges faced with JavaScript in complex projects. TypeScript is a typed superset of JavaScript that allows developers to convert existing JavaScript projects into ones containing type definitions and other features that make maintenance and scalability easier. Ably's approach to migration involved setting up a TypeScript configuration, converting the most frequently used files first, and then progressively converting other files while ensuring tests still passed. The benefits of migrating to TypeScript include better error handling, improved code maintenance, and easier onboarding for new engineers.