JS将对象数组转换为JSON GroupBy格式

function groupBy(arr, property) {
  return arr.reduce(function (acc, obj) {
    var key = obj[property];
    if (!acc[key]) {
      acc[key] = [];
    }
    acc[key].push(obj);
    return acc;
  }, {});
}

var data = [
  { name: 'Alice', age: 25, city: 'New York' },
  { name: 'Bob', age: 30, city: 'London' },
  { name: 'Charlie', age: 35, city: 'New York' },
  { name: 'Dave', age: 40, city: 'London' }
];

var result = groupBy(data, 'city');
console.log(result);

{
  'New York': [
    { name: 'Alice', age: 25, city: 'New York' },
    { name: 'Charlie', age: 35, city: 'New York' }
  ],
  'London': [
    { name: 'Bob', age: 30, city: 'London' },
    { name: 'Dave', age: 40, city: 'London' }
  ]
}