LESSON 1.3
Literal types and const assertions
Learn key techniques and workflows in TypeScript for Application Developers.
5m
intermediate
19,825 students
Overview
Widening is why your string turned into string. A const assertion keeps the literal, which is what makes union-of-literals modelling work.
In this lesson you will:
- Understand literal widening and when it happens
- Freeze a literal shape with as const
- Derive a union of allowed values from a constant array
Pro Tip
Use caching and revalidation wisely to ensure your app stays fast and data remains fresh without unnecessary requests.