Overload class method return type

[lone grove]

m.a.t.t.t#0

Playground Link

Preview:ts class X { foo(xyz?: false): number foo(xyz: true): string { return xyz === true ? "abc" : 10 } }

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[dawn wharf]

Is it possible to make this work?

[molten trout]

The implementation needs to handle the most generic case. Something like this:

class X {
  foo(xyz?: false): number
  foo(xyz: true): string
  foo(xyz?: boolean): string | number {
    return xyz === true ? 'abc' : 10
  }
}

[dawn wharf]

Oh cool, thanks Evan. It looks like the compiler won't check for correctness against overloads though, is that right? e.g. if I change the 10 to "10" it won't check the false branch is correctly returning a number

[vague fox]

yes, overloads aren't checked

[dawn wharf]

thanks 🙂