How can I retrieve the default option from a list of options?
type
export type Unpacked<T> = T extends Array<infer U> ? U : T;
interface
getDefaultValue?: <T extends Option[]>(options: T) => Unpacked<T>;
Example
const options = [
{label: "New York", value: 38 },
{label: "Washington", value: 39 }
]
then return type of getDefaultValue must be 38 | 39
Incorrect test is
getDefaultValue={(options: Option[]) => any string}
But I have got error
Type 'string' is not assignable to type 'Unpacked<T>'.UPD
https://codesandbox.io/s/inspiring-galileo-ndto7l?file=/src/App.tsx
export type Unpacked<T> = T extends Array<infer U> ? U : T;
type Option = { label: string; id: number };
const getValues = <T extends Option[]>(anyOptions: T): Unpacked<T> => {
return anyOptions[0].id;
};
const options: Option[] = [
{ label: "New York", id: 38 },
{ label: "Washington", id: 39 }
];
/** result must be any id from options.*/
/** In current case type of result must be 38 | 39 */
const result = getValues(options);
export default function App() {
return null;
}