Updating Deeply Nested Arrays with Spread Operator

// Given a deeply nested array
const nestedArray = [
    { id: 1, items: ['a', 'b', 'c'] },
    { id: 2, items: ['d', 'e', { sub: ['x', 'y', 'z'] }] },
    { id: 3, items: ['f', 'g', 'h'] }
];

// Suppose we want to update 'y' to 'Y' in the sub-array of the second element
const updatedNestedArray = nestedArray.map(item => {
    if (item.id === 2) {
        return {
            ...item, // Copy the item object
            items: item.items.map(subItem => {
                if (typeof subItem === 'object' && subItem.sub) {
                    // It's the object containing the sub-array
                    return {
                        ...subItem, // Copy the subItem object
                        sub: subItem.sub.map(subValue => subValue === 'y' ? 'Y' : subValue) // Update the sub-array
                    };
                }
                return subItem; // Return the subItem unchanged if it's not the object we're looking for
            })
        };
    }
    return item; // Return item unchanged if it's not the one we're looking for
});

console.log(updatedNestedArray);