const t1 = [
    { x: 1, y: 2 },
    { x: 3, y: 4 },
    { x: 5, y: 6 }
]  //?  [1, 2, 3, 4, 5, 6]


t1.flatMap(c => [c.x, c.y])

const orders = [
    {
        orderId: 42,
        items: [
            {name: 'soap', price: 1.99},
            {name: 'shampoo', price: 4.99}
        ]
    },
    {
        orderId: 1337,
        items: [
            {name: 'toothpaste', price: 5.59},
            {name: 'toothbrush', price: 8.99}
        ]
    }
];

orders.flatMap(o => o.items.map(i => i.name));