typescript-interface-vs-type

Prefer a TypeScript interface for defining plain object shapes to enable declaration merging and better compiler performance. Use type aliases only when you need advanced features like unions, mapped types, conditional types, or tuples.

Declaration merging allows multiple interface definitions with the same name to combine automatically, extending API flexibility. Using interface extends for object shape extensibility preserves type safety and improves compiler performance compared to type aliases.

Use type aliases to handle union types and tuples in TypeScript, because interfaces cannot represent these advanced type constructs. Type aliases provide the necessary flexibility for modeling conditional types and mapped types accurately.

Avoid using a TypeScript interface when modeling union types, tuples, mapped types, or conditional types, as interfaces only support plain object shapes and class implementations. Type aliases are required for these advanced type features.

TypeScript compiler performance improves when you prefer interfaces for object shapes, because interfaces support declaration merging and extensibility more efficiently. Reserve type aliases for advanced constructs like unions to avoid performance pitfalls.

Yes, you can implement a TypeScript interface in a class to enforce object shape structure and use interface extends for subsequent extensibility. This approach maintains type safety and ensures better compiler performance than type aliases.