var arr = [];

for (var i = 0; i < 12345; i++) {

  arr[i] = i;

}

​

function reduceFilterMap(filterSelector, valueSelector) {

    return [

        (previousValue, currentValue, currentIndex) => {

            const shouldBeAdded = filterSelector(currentValue, currentIndex);

            if (shouldBeAdded) {

                previousValue.push(valueSelector(currentValue, currentIndex));

            }

​

            return previousValue;

        },

        [],

    ];

}