Alexandroppolus

const handleClickRMB = useCallback((event) => {
    event.preventDefault();

    let index1 = Number(event.path[0].attributes.pos1.value);
    let index2 = Number(event.path[0].attributes.pos2.value);
    let pressedCell = board[index1][index2];
    setFlagsLeft(flagsLeft => {
        if ((!pressedCell.opened) && (flagsLeft !== 0)) {
            const marked = pressedCell.marked;
            pressedCell.mark();
            changeOneCell(index1, index2, pressedCell);
            return marked ? flagsLeft + 1 : flagsLeft - 1;
        }
        return flagsLeft;
    });
}, [setFlagsLeft, changeOneCell]);

useEffect(() => {
    document.addEventListener('contextmenu', handleClickRMB, false);
    return () => document.removeEventListener('contextmenu', handleClickRMB, false);
}, [handleClickRMB]);

function createMap(arr) {
    const map = new Map();
    
    arr.forEach(a => {
        let childs = map.get(a.parentId);
        if (!childs) {
            map.set(a.parentId, childs = []);
        }
        childs.push(a);
    });

    return map;
}

function filter(map, initial) {
    const result = (map.get(initial) || []).slice();
    for (let i = 0; i < result.length; ++i) {
        result.push(...(map.get(result[i].id) || []));
    }

    return result;
}

// использование
const initial = 1
const arr = [
                    { name: '1', parentId: 1, id: 2 },
                    { name: '2', parentId: 2, id: 3 },
                    { name: '3', parentId: 1, id: 4 },
                    { name: '3', parentId: 4, id: 5 }
                ];

var map = createMap(arr);
console.log(filter(map, initial));
console.log(filter(map, 2));

const full = '#'.repeat(7); // полная строка
for (let i = 1; i <= 7; i++){
    console.log(full.substr(0, i));
}