I am trying to define a type where the favoriteFruit property's value must be an item in options array. Where the options array is dynamic/unknown (making it impossible to use union types "|").
const options = ["apple", "orange", "kiwi"]; // Dynamic list that can be modified in the future
type Person = {
name: string;
favoriteFruit: /* --- val in [...options] --- */
};
const personA:Person = {name: "Jack", favoriteFruit: "apple"}; // OK
const personB:Person = {name: "John", favoriteFruit: "orange"}; // OK
const personC:Person = {name: "Jane", favoriteFruit: "banana"}; // ERROR
I found this : How to convert array of strings to typescript types? .
const arr = ["foo", "bar", "loo"] as const
type arrTyp = typeof arr[number]; // "foo" | "bar" | "loo"
I hope this is what you are looking for
[UPDATED]
const options = ["apple", "orange", "kiwi"] as const; // Dynamic list that can be modified in the future
type optionsType = typeof options[number];
type Person = {
name: string;
favoriteFruit: optionsType;/* --- val in [...options] --- */
};
const personA:Person = {name: "Jack", favoriteFruit: "apple"}; // OK
const personB:Person = {name: "John", favoriteFruit: "orange"}; // OK
const personC:Person = {name: "Jane", favoriteFruit: "banana"}; // ERROR
console.log(personC)
you can keep your options list dynamic