It provides syntax sugar to simplify defining classes, interfaces, lambda functions and so on. Strong type checking is helpful for finding and fixing bugs before even running user scripts.
Version 7.25 upgrades the built-in TypeScript compiler to version 1.5.
Version 7.70 upgrades the built-in TypeScript compiler to version 1.8.10.
Device Monitoring Studio internally has TypeScript declarations for all supported objects, their properties and methods. This allows automatic syntax and type check when user script is launched.