TypeScript · Advanced

TypeScript at application boundaries

Validate unknown data, model state transitions and preserve type relationships.

Prerequisite: TypeScript foundations · 80 minutes of guided study

3 focused lessons; use tsc --strict for full type checking.

Open interactive course →

Engineering practice

Validate untrusted JSON at the boundary
unknown requires evidence; a type assertion supplies none.
25 min →
Model legal state transitions
A reducer makes transition rules reviewable and testable.
30 min →
Keep generic grouping type safe
Preserve the relationship between records and keys.
25 min →