Given below is an array of objects, need to create sub-array in it with common make key, also all sub-array and main array needs to be sorted as follows:

1. the main array to be sorted on make key alphabetically.
2. sub-arrays to be sorted ASC on the basis of the year.

Input Array:

const cars = [
    {
        "make": "audi",
        "model": "r8",
        "year": "2006"
    }, {
        "make": "audi",
        "model": "s5",
        "year": "2005"
    }, {
        "make": "ford",
        "model": "mustang",
        "year": "2012"
    }, {
        "make": "ford",
        "model": "fusion",
        "year": "2015"
    }, {
        "make": "kia",
        "model": "optima",
        "year": "2012"
    },
];

Desired Array:

const cars = [
    {
      "make": "audi",
      "list": [
        {
          "model": "s5",
          "year": "2005",
        },
        {
          "model": "r8",
          "year": "2006",
        },
      ],
    },
    {
      "make": "ford",
      "list": [
        {
          "model": "mustang",
          "year": "2012",
        },
        {
          "model": "fusion",
          "year": "2015",
        },
      ],
    },
    {
      "make": "kia",
      "list": [
        {
          "model": "optima",
          "year": "2012",
        },
      ],
    },
  ];

What I have tried yet:

let filteredData = [];

cars.forEach((value)=>{

    var foundIndex = filteredData.findIndex( car => car.make === value.make );

    if(foundIndex != -1){

        let carData = filteredData[foundIndex];
        const {list} = carData;
        let nextObj = {'model': value.model, 'year': value.year};
        const newData = [...list, nextObj];
        carData['list'] = newData;
        filteredData[foundIndex] = carData;

     }else{
          
        let values = {'model': value.model, 'year': value.year};    
        let data = [values];
        let obj = {'make':value.make, 'list': data};
        filteredData.push(obj);
     }
});
const sortedCars = filteredData.sort((a, b) => a.make.localeCompare(b.make));

Any optimal solution for this to make it better is welcomed.

CodePudding user response：

let filteredData = [];

cars.forEach((value)=>{

    var foundIndex = filteredData.findIndex( car => car.make === value.make );

    if(foundIndex != -1){

        let carData = filteredData[foundIndex];
        const {list} = carData;
        let nextObj = {'model': value.model, 'year': value.year};
        let newData = [...list, nextObj];
        
        newData.sort((a, b) => a.year.localeCompare(b.year));
        carData['list'] = newData;
        filteredData[foundIndex] = carData;

     }else{
          
        let values = {'model': value.model, 'year': value.year};    
        let data = [values];
        let obj = {'make':value.make, 'list': data};
        filteredData.push(obj);
     }
});
const sortedCars = filteredData.sort((a, b) => a.make.localeCompare(b.make));

CodePudding user response：

Because javascript objects sort integer properties by default you can 'group by' year within each list and then map the resulting object values to arrays. The outer array will need to be sorted explicitly.

const cars = [
    { make: 'ford', model: 'fusion', year: '2015' },
    { make: 'audi', model: 'r8', year: '2006' },
    { make: 'audi', model: 's5', year: '2005' },
    { make: 'ford', model: 'mustang', year: '2012' },
    { make: 'kia', model: 'optima', year: '2012' },
];

const result = Object.values(
      cars.reduce((a, { make, year, ...rest }) => {
          a[make] ??= { make, list: {} };
          a[make].list[year] ??= [];
          a[make].list[year].push({ year, ...rest });

          return a;
      }, {}))
    .map(({ make, list }) => ({ make, list: Object.values(list).flat() }))
    .sort((a, b) => a.make.localeCompare(b.make));

console.log(result);

Alternatively, you can sort (a copy) of the array by year before reducing, and then sort the result by make afterwards. Here using a for...of loop instead of reduce().

const cars = [
    { make: 'ford', model: 'fusion', year: '2015' },
    { make: 'audi', model: 'r8', year: '2006' },
    { make: 'audi', model: 's5', year: '2005' },
    { make: 'ford', model: 'mustang', year: '2012' },
    { make: 'kia', model: 'optima', year: '2012' },
];

const grouped = {};

for (const { make, ...rest } of [...cars].sort((a, b) => a.year - b.year)) {
    (grouped[make] ??= { make, list: [] }).list.push({ ...rest });
}

const result = Object.values(grouped).sort((a, b) =>
    a.make.localeCompare(b.make)
);

console.log(result);