Multiple optional function arguments

[anilanar]

declare fn(str?: string, num?: number): void

Test

fn(5);

Actual Result

fn(5);
   ^ number. This type is incompatible with
fn(str?: string, num?: number): void;
         ^^^^^^ string.

Expected Result
I assume it should not error for the following uses:

fn();
fn('str');
fn(5);
fn('str', 5);

[vkurchatkin]

I think it works as expected. You need to add an overload for this to work

[anilanar]

Shouldn't this be documented somewhere though (even if it works as expected)?

[samwgoldman]

@vkurchatkin is right on both counts, this is working as designed and you might be looking for function overloads. You might also be looking for union types, i.e., function f(arg: number | string) { ... }.

Contributions to the docs are very welcome!