javascript - 如何映射和减少对象数组？

Question

如何从以下对象数组中计算价格:

const cars = [
{
    price: 10000,
    car: 'audi'
},
{
    price: 10000,
    car: 'audi'
},
{
    price: 10000,
    car: 'nissan'
},
{
    price: 10000,
    car: 'nissan'
},
{
    price: 20000,
    car: 'mazda'
},
{
    price: 10000,
    car: 'nissan'
},
];

这样我就可以获得一组对象，以及总价格:

const cars = [
{
    price: 20000,
    car: 'audi'
},
{
    price: 30000,
    car: 'nissan'
},
{
    price: 20000,
    car: 'mazda'
}
];

尝试映射数组，然后减少，但是如何保留结构，以便取回对象数组？这是不正确的:

 const newCarsArray = cars.map(item => {
     return(
        //cars.reduce ?
     )
 });

Answer 1

您可以将数组减少为由汽车键入的对象，保存总数，然后将其转换回您的格式非常简单

const cars = [{price: 10000, car: 'audi'},{price: 10000, car: 'audi'},{price: 10000, car: 'nissan'},{price: 10000, car: 'nissan'}, {price: 20000,        car: 'mazda'}, {price: 10000, car: 'nissan'}];

var map = cars.reduce((map, car) => {
  map[car.car] = map[car.car] ? map[car.car] + car.price : car.price;
  return map;
}, {});

console.log(map); // {audi: 20000, nissan: 30000, mazda: 20000}

var array = Object.keys(map).map( car => ({car: car, price: map[car]}));

console.log(array);