typescript-interface-vs-type

Use a TypeScript interface for object shapes that may be extended later, and prefer type aliases for simple unions or type-only constructs. This distinction ensures consistent object typing and easier maintenance across your codebase.

TypeScript declaration merging combines multiple interface declarations with the same name into a single definition. This mechanism allows you to extend object shapes across files, a pattern unavailable when using type aliases for the same purpose.

Yes, TypeScript type aliases are the recommended approach for creating unions and mapped types. They provide the flexibility needed for these type-only constructs, whereas interfaces are restricted to defining object shapes.

The best way to model API responses in TypeScript is using interfaces for data structures that may be extended later. This approach supports declaration merging and ensures compatibility with common object typing patterns.

You should not use a TypeScript interface when you need simple unions, mapped types, or other type-only constructs. In these scenarios, type aliases are the correct choice to avoid inconsistent object typings and maintenance challenges.