How to check if value exists inside javascript Flow type

Question

I have a Flow type defined as

export type fruit = 'apple' | 'orange' | 'pear';

What I want to do is validate a string and see if it matches any of the values defined in this type.

Is there a way to do this?

Answer 1

The best approach is to use an array then validate by using Array#includes like this.

const fruits = ['apple', 'orange', 'pear'];
const isValid = anyFruit => fruits.includes(anyFruit);

console.log(isValid("apple"));
console.log(isValid("orange"));
console.log(isValid("pear"));
console.log(isValid("banana"));