In Typescript, how can I specify the return type of a function that can return multiple types?

I have a reusable method getFilters that can return a number of different types

getFilters(): IListFilteringType {...}
type IListFilteringTypeMultiSelect = (string | number)[];
type IListFilteringType = boolean | string | number | IListFilteringTypeMultiSelect;

When I call getFilters how can I specify that I know that the returned value with be of type IListFilteringTypeMultiSelect and not one of the other possible values of IListFilteringType?

Thank you

Answer

If you are sure about the type of the return of the function for a particular execution, you could cast the return value using as.

const variable = functionResponse as IListFilteringTypeMultiSelect;