Filter -> Map -> Reduce

var arr = [1, 2, 3, 4, 5, 6, 7];
console.log('arr', arr);
var arr_filter = arr
    .filter((_, i) => {
        return _ % 2 == 0;
    });
console.log('arr_filter', arr_filter);
var arr_map = arr_filter.map((_, i) => {
    return _ * 2;
});
console.log('arr_map', arr_map);
var arr_reduce = arr_map.reduce((accumulator, currentValue) => {
    return accumulator + currentValue;
});
console.log('arr_reduce', arr_reduce);