以函数和自定义对象收集器为参数进行分组

// 假设有一个包含学生信息的数组
const students = [
  { name: 'Alice', age: 18, grade: 'A' },
  { name: 'Bob', age: 17, grade: 'B' },
  { name: 'Charlie', age: 18, grade: 'A' },
  { name: 'David', age: 17, grade: 'C' },
  { name: 'Eve', age: 18, grade: 'B' }
];

// 定义一个以年龄为条件进行分组的函数
function groupByAge(result, student) {
  const age = student.age;
  if (!result[age]) {
    result[age] = [];
  }
  result[age].push(student);
  return result;
}

// 使用reduce()方法进行分组
const groupedStudents = students.reduce(groupByAge, {});

// 打印分组结果
console.log(groupedStudents);

{
  17: [
    { name: 'Bob', age: 17, grade: 'B' },
    { name: 'David', age: 17, grade: 'C' }
  ],
  18: [
    { name: 'Alice', age: 18, grade: 'A' },
    { name: 'Charlie', age: 18, grade: 'A' },
    { name: 'Eve', age: 18, grade: 'B' }
  ]
}