Allow filtering in MapEntries

[stefaanv]

If the mapEntries() code is updates as below, it's function would extend to filtering the properties of the object

const mapEntries = <
    TKey extends string | number | symbol,
    TValue,
    TNewKey extends string | number | symbol,
    TNewValue,
>(
    obj: Record<TKey, TValue>,
    toEntry: (key: TKey, value: TValue) => [TNewKey, TNewValue] | undefined
): Record<TNewKey, TNewValue> => {
    if (!obj) return {} as Record<TNewKey, TNewValue>
    return Object.entries(obj).reduce(
        (acc, [key, value]) => {
            const alteredEntry = toEntry(key as TKey, value as TValue)
            if (alteredEntry) acc[alteredEntry[0]] = alteredEntry[1]
            return acc
        },
        {} as Record<TNewKey, TNewValue>
    )
}

The example could become

const ra = {
    name: 'Ra',
    power: 'sun',
    rank: 100,
    culture: 'egypt'
}

mapEntries(ra, (key, value) =>  (key !== 'power') ? [key.toUpperCase(), `${value}`] : undefined)
// returns { "NAME": "Ra", "RANK": "100", "CULTURE": "egypt" }

[stefaanv]

Pull request 367 created to resolv this issue