With TypeScript 3.4, const assertions were added to the language. A const assertion is a special kind of type assertion in which the const keyword is used instead of a type name. By Marius Schulz.
TypeScript has a special kind of literal type that’s known as a non-widening literal type. As the name suggests, non-widening literal types will not be widened to a more generic type. For example, the non-widening string literal type “GET” will not be widened to string in cases where type widening would normally occur.
The article dives straight in:
- Motivation for const Assertions
- String Literal Types
- Literal Type Widening
- Non-Widening Literal Types
- const Assertions for Literal Expressions
- Using TypeScript Enums
- const Assertions for Other Types
Plenty of code examples in this to the point article!
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