tsafe
Search
⌃K
Links

ReturnType

Like the builtin helper but more convenient to use.
There is two major pain point with the default ReturnType:

Used with async function

If you have a function like:
type Shape = {};
async function getShape(): Promise<Shape> {
return {};
}
And you are trying to extract Shape, when you use the default return type:
type shape = ReturnType<typeof getShape>;
// ^ shape is Promise<Shape> 😤
With tsafe's ReturnType
import type { ReturnType } from "tsafe";
​
type shape = ReturnType<typeof getShape>;
// ^ shape is Shape 😊

Used with function that can be undefined

Let's say we have an interface defined as such:
export type Api = {
getShape?: () => Shape;
};
And we want to extract the type Shape, using the default ReturnType we have to do:
type shape = ReturnType<NonNullable<Api["getShape"]>>;
With the ReturnType of tsafe you don't need NonNullable
import type { ReturnType } from "tsafe";
​
type shape = ReturnType<Api["getShape"]>;
Last modified 2mo ago