function groupBy(data, property) {
  return data.reduce((acc, obj) => {
    const key = obj[property];
    if (!acc[key]) {
      acc[key] = [];
    }
    acc[key].push(obj);
    return acc;
  }, {});
}
groupBy(people, 'age');

下面是您自己的groupBy函数，它是来自https://github.com/you-dont-need/You-Dont-Need-Lodash-Underscore的代码的泛化

函数groupBy(xs, f) { 返回x。减少((r, v, i, a、k = f (v)) = > ((r [k] | | (r [k] = [])) .push (v), r), {}); ｝ Const cars = [{make: 'audi'，型号:'r8'，年份:'2012'}，{make: 'audi'，型号:'rs5'，年份:'2013'}，{make: 'ford'，型号:'mustang'，年份:'2012'}，{make: 'ford'，型号:'fusion'，年份:'2015'}，{make: 'kia'，型号:'optima'，年份:'2012'}]; const result = groupBy(cars， (c) => c.make); console.log(结果);

对于key可以为null的情况，我们希望将它们分组为其他

var cars = [{'make':'audi','model':'r8','year':'2012'},{'make':'audi','model':'rs5','year':'2013'},{'make':'ford','model':'mustang','year':'2012'},{'make':'ford','model':'fusion','year':'2015'},{'make':'kia','model':'optima','year':'2012'},
            {'make':'kia','model':'optima','year':'2033'},
            {'make':null,'model':'zen','year':'2012'},
            {'make':null,'model':'blue','year':'2017'},

           ];


 result = cars.reduce(function (r, a) {
        key = a.make || 'others';
        r[key] = r[key] || [];
        r[key].push(a);
        return r;
    }, Object.create(null));

下面是一个受到Java中的collections . groupingby()启发的解决方案:

function groupingBy(list, keyMapper) { 返回列表。reduce((accummalatorMap, currentValue) => { const key = keyMapper(currentValue); 如果(! accummalatorMap.has(键)){ accummalatorMap。集(关键,[currentValue]); }其他{ accummalatorMap。集(键,accummalatorMap.get(关键).push (currentValue)); ｝ 返回accummalatorMap; }， new Map()); ｝

这将给出一个Map对象。

/ /使用 const cars = groupingBy(cars, car => car.make);

这是另一个解决方案。按照要求。

我想创建一个新的汽车对象数组，由make分组:

function groupBy() {
  const key = 'make';
  return cars.reduce((acc, x) => ({
    ...acc,
    [x[key]]: (!acc[x[key]]) ? [{
      model: x.model,
      year: x.year
    }] : [...acc[x[key]], {
      model: x.model,
      year: x.year
    }]
  }), {})
}

输出:

console.log('Grouped by make key:',groupBy())

你也可以像这样使用数组#forEach()方法:

const cars = [{ make: 'audi', model: 'r8', year: '2012' }, { make: 'audi', model: 'rs5', year: '2013' }, { make: 'ford', model: 'mustang', year: '2012' }, { make: 'ford', model: 'fusion', year: '2015' }, { make: 'kia', model: 'optima', year: '2012' }]; let newcars = {} cars.forEach(car => { newcars[car.make] ? // check if that array exists or not in newcars object newcars[car.make].push({model: car.model, year: car.year}) // just push : (newcars[car.make] = [], newcars[car.make].push({model: car.model, year: car.year})) // create a new array and push }) console.log(newcars);