@formatjs/intl-localematcher/lib/abstract/CanonicalizeUValue.js

Intl.LocaleMatcher ponyfill

import { invariant } from './utils';
export function CanonicalizeUValue(ukey, uvalue) {
    // TODO: Implement algorithm for CanonicalizeUValue per https://tc39.es/ecma402/#sec-canonicalizeuvalue
    var lowerValue = uvalue.toLowerCase();
    invariant(ukey !== undefined, "ukey must be defined");
    var canonicalized = lowerValue;
    return canonicalized;
}