Types vs Interfaces: Which is More Performant?

What are the performance differences between types and interfaces in TypeScript?

In TypeScript, both types and interfaces can be used to define object shapes, but they have some performance differences. Generally, interfaces are more performant for large codebases because they can be merged and extended, which can lead to better optimization by the TypeScript compiler.

Can you explain how merging interfaces affects performance?

Merging interfaces allows TypeScript to combine multiple declarations into a single interface. This can reduce redundancy and improve maintainability, which indirectly enhances performance by minimizing the amount of code the compiler needs to process.

Are there scenarios where using types is better than interfaces?

Yes, types are often better for union types or when you need to define a more complex type structure. They can also be more concise in certain situations, which can lead to clearer code.

What about runtime performance? Does it differ?

At runtime, both types and interfaces are erased, meaning they don't have a direct impact on performance. The choice between them mainly affects compile-time checks and code organization.