Сортировка массива на основе значения вложенного объекта

function sortCustomers(customers, route) {
    const order = ({ displayOrder }) => displayOrder.find(o => route in o)[route];
    customers.sort((a, b) => order(a) - order(b));
    return customers;
}

const customers = [{ name: 'John', displayOrder: [{ route1: 1 }, { route2: 3 }] }, { name: 'Julie', displayOrder: [{ route1: 2 }, { route2: 1 }] }, { name: 'Betsy', displayOrder: [{ route1: 3 }, { route2: 2 }] }];

console.info(sortCustomers(customers, 'route2'));

.as-console-wrapper { max-height: 100% !important; top: 0; }

const customers = [
  {
    name: 'John',
    displayOrder: [{ route1: 1 }, { route2: 3 }],
  },
  {
    name: 'Julie',
    displayOrder: [{ route1: 2 }, { route2: 1 }],
  },
  {
    name: 'Betsy',
    displayOrder: [{ route1: 3 }, { route2: 2 }],
  },
];

function sortCustomers(customers, route) {
  const index = route == "route2" ? 1 : 0;
   let sorted = customers.sort((a, b) => {
    return a.displayOrder[index][route] - b.displayOrder[index][route]
  })
  
   // only listed name obj
    const result = sorted.map(obj => obj.name);
   
  return result;
}

const route = 'route2';

const result = sortCustomers(customers, route);
console.info(result)