将对象数组修改为按键分组的多维数组

function groupBy(arr, key) {
  const result = [];
  
  for (let obj of arr) {
    const keyValue = obj[key];
    const group = result.find(item => item.key === keyValue);
    
    if (group) {
      group.values.push(obj);
    } else {
      result.push({ key: keyValue, values: [obj] });
    }
  }
  
  return result;
}

// 示例数据
const data = [
  { name: 'Tom', age: 20, gender: 'Male' },
  { name: 'Jerry', age: 22, gender: 'Male' },
  { name: 'Alice', age: 20, gender: 'Female' },
  { name: 'Bob', age: 22, gender: 'Male' },
  { name: 'Eve', age: 20, gender: 'Female' }
];

// 按年龄分组
const result = groupBy(data, 'age');
console.log(result);

[
  { key: 20, values: [
    { name: 'Tom', age: 20, gender: 'Male' },
    { name: 'Alice', age: 20, gender: 'Female' },
    { name: 'Eve', age: 20, gender: 'Female' }
  ]},
  { key: 22, values: [
    { name: 'Jerry', age: 22, gender: 'Male' },
    { name: 'Bob', age: 22, gender: 'Male' }
  ]}
]