打字稿：与基本类型平行的自定义类型被忽略

Question

Expectation: If I create a custom type that parallels an existing type I expect to see variables assigned that type maintain that type and not fallback to to the paralleled base type. The function f below should return a Dog type instead a string type.

type Dog = string;

const f = (dog: Dog): Dog => {
    return dog;
};

Reality:

Is there a reason why Typescript does this? Is this a bug? I realize both approaches are by definition equivalent but I would like to use my custom types for readability. Any thoughts?

Answer 1

I think this will help you learn more about aliases.

Aliasing doesn't actually create a new type - it creates a new name to refer to that type.