type-value-space

Type space in TypeScript refers to compile-time type-level definitions like interfaces and type aliases, whereas value space represents runtime entities such as classes, enums, and variables that actually exist during execution.

To fix TypeScript errors from mixing type and value semantics, analyze whether the symbol is a compile-time type or a runtime value, then adjust declarations or use typeof to safely reference value-space entities in type positions.

Your TypeScript interface disappears at runtime because interfaces exist solely in type space for compile-time checking, meaning they are completely erased during transpilation and leave no trace in the executed JavaScript value space.

The typeof operator in TypeScript queries a value-space entity to extract its type-space representation, allowing destructured runtime objects to inform compile-time type definitions without duplicating structural property definitions.

TypeScript enums exist in both type space and value space simultaneously, functioning as compile-time types for variable annotations while also emitting real runtime JavaScript objects that hold actual values during execution.

Limitations of using type aliases in value space contexts include their complete erasure during compilation, meaning they cannot be instantiated, referenced at runtime, or used in JavaScript logic, strictly confining them to type space.