Is it possible to define a type that resolves to one of two given types?

Question

Assuming I have several functions that return the same number | Date type is it possible to define a type that will be one of these two?

I.e. instead of:

foo1(): number | Date {}
foo2(): number | Date {}

is it possible to have:

foo1(): NumberOrDate {}
foo2(): NumberOrDate {}

?

Or is there any other idea on how to stay DRY and not repeat number | Date?

Does this answer your question? [Does TypeScript allow type aliases?](https://stackoverflow.com/questions/21839692/does-typescript-allow-type-aliases) — possum, Mar 13 '23 at 10:50
@possum the question is not very similar to mine but one of the answers covers my problem indeed so I wouldn't call it a perfect match. — S. Pauk, Mar 13 '23 at 10:53

score 2 · Accepted Answer · answered Mar 13 '23 at 10:49

2

You can just declare a type alias for the union:

type NumberOrDate = number | Date

function foo1(): NumberOrDate { return 1;}
function foo2(): NumberOrDate { return new Date}

answered Mar 13 '23 at 10:49

1 Answers1