Set and Map lookup example

gistfile1.js

const interestSurcharge = new Set(['AL']);
const flagshipOriginationFee = new Set(['AK', 'AZ', 'AR', 'CA', 'CO', 'CT', 'DE', 'DC', 'FL', 'GA', 'HI',
    'ID', 'IA', 'KS', 'KY', 'LA', 'ME', 'MS', 'MO', 'NM', 'ND', 'OH', 'OR',
    'RI', 'SC', 'SD', 'UT', 'VA', 'WV', 'WI', 'WY']);
const documentPreparation = new Set(['IL']);
const nonrefundablePrepaidFinanceCharge = new Set(['IN']);
const notApplicable = new Set(['MD', 'MA', 'MN', 'MT', 'NV', 'NH', 'NJ', 'NY', 'NC', 'PA', 'VT']);
​
const feeNameMap = new Map([
    [flagshipOriginationFee, 'Flagship Origination Fee'],
    [interestSurcharge, 'Interest Surcharge'],
    [documentPreparation, 'Document Preparation'],
    [nonrefundablePrepaidFinanceCharge, 'Nonrefundable Prepaid Finance Charge'],
    [notApplicable, 'N/A'],
]);
​
function determineFeeName(stateAbbr) {
    const feeTypes = feeNameMap.entries();
    let entry = feeTypes.next();
    while (entry.done === false) {
        const [appliesTo, feeName] = entry.value;
        if (appliesTo.has(stateAbbr)) return feeName;
        entry = feeTypes.next();
    }
}
​
console.log(determineFeeName('CO')); // Flagship Origination Fee
console.log(determineFeeName('IN')); // Nonrefundable Prepaid Finance Charge