LESSON 4.2
Typing external data at the boundary
Learn key techniques and workflows in TypeScript for Application Developers.
7m
intermediate
10,686 students
Overview
Data from the network is unknown until you prove otherwise. A runtime schema validates it once and gives you a static type for free.
In this lesson you will:
- Parse unknown input instead of casting it
- Derive a static type from a runtime schema
- Fail loudly at the boundary rather than deep inside
Pro Tip
Use caching and revalidation wisely to ensure your app stays fast and data remains fresh without unnecessary requests.