@yobta/validator/lib/oneOf/oneOf.js

Tree-shakable es6 validator

import { rule } from '../rule/rule.js';
export const oneOfMessage = items => `It should be one of: ${items}`;
export const oneOf = (items, message = oneOfMessage) => rule((input = '') => {
    if (items.has(input)) {
        return input;
    }
    if (input === '') {
        return undefined;
    }
    throw new Error(message(items));
});