按JavaScript中的键值将集合分组为集合集合

function groupBy(collection, key) {
  var groupedCollection = {};
  
  collection.forEach(function(element) {
    var elementKey = element[key];
    
    if (!groupedCollection[elementKey]) {
      groupedCollection[elementKey] = [];
    }
    
    groupedCollection[elementKey].push(element);
  });
  
  return groupedCollection;
}

// 示例用法
var people = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 30 },
  { name: 'Charlie', age: 25 },
  { name: 'Dave', age: 30 }
];

var groupedPeople = groupBy(people, 'age');
console.log(groupedPeople);

{
  25: [
    { name: 'Alice', age: 25 },
    { name: 'Charlie', age: 25 }
  ],
  30: [
    { name: 'Bob', age: 30 },
    { name: 'Dave', age: 30 }
  ]
}