如何在 JavaScript 中强制减少为不按字母顺序排序

Question

I need to group by my elements in array so I did in that way:

const cars = [{
        make: "vw",
        model: "passat",
        year: "2012"
    },
    {
        make: "vw",
        model: "golf",
        year: "2013"
    },
    {
        make: "ford",
        model: "mustang",
        year: "2012"
    },
    {
        make: "ford",
        model: "fusion",
        year: "2015"
    },
    {
        make: "kia",
        model: "optima",
        year: "2012"
    }
];

let group = cars.reduceRight((r, a) => {
  r[a.make] = [...r[a.make] || [], a];
  return r;
 }, []);

console.log(cars)
console.log(group)

But unfortunatelly after that grouping with reduce the order of elements is wrong. VW Group is at the end , how can I fource reduce to not sorting elements, or maybe there is better way to group elements?

DEMO: https://www.w3schools.com/code/tryit.asp?filename=GG4TVX5J3X3A

Answer 1

reduceRight applies the reduce from right to left. Just don't use the Right variant and it'll be in the original order.

 const cars = [{ make: "vw", model: "passat", year: "2012" }, { make: "vw", model: "golf", year: "2013" }, { make: "ford", model: "mustang", year: "2012" }, { make: "ford", model: "fusion", year: "2015" }, { make: "kia", model: "optima", year: "2012" } ]; let group = cars.reduce((r, a) => { r[a.make] = [...r[a.make] || [], a]; return r; }, {}); console.log(cars) console.log(group)

There was a bug in your original code, you were assigning properties of an array. There's no point to this; use an object instead.