JavaScript中按姓氏与年龄分组生成连续order字段的实现

需求说明 #

需要将给定的JavaScript数组转换为包含order字段的新数组，规则如下：

• 当元素的surname（姓氏）和age（年龄）同时相同时，共享同一个order值，不递增计数
• 其余元素按顺序递增order数值

原始数组 #

[
  {name:"jhon",surname:"connor",age:21},
  {name:"jhonny",surname:"lator",age:22},
  {name:"celia",surname:"mcgregor",age:23},
  {name:"raul",surname:"fernandez",age:25},
  {name:"marcela",surname:"fernandez",age:25},
  {name:"omar",surname:"caster",age:26},
  {name:"luna",surname:"potter",age:30},
  {name:"harry",surname:"potter",age:30},
]

目标数组 #

[
  {order:1,name:"jhon",surname:"connor",age:21},
  {order:2,name:"jhonny",surname:"lator",age:22},
  {order:3,name:"celia",surname:"mcgregor",age:23},
  {order:4,name:"raul",surname:"fernandez",age:25},
  {order:4,name:"marcela",surname:"fernandez",age:25},
  {order:5,name:"omar",surname:"caster",age:26},
  {order:6,name:"luna",surname:"potter",age:30},
  {order:6,name:"harry",surname:"potter",age:30},
]

解决方案代码 #

const originalArray = [
  {name:"jhon",surname:"connor",age:21},
  {name:"jhonny",surname:"lator",age:22},
  {name:"celia",surname:"mcgregor",age:23},
  {name:"raul",surname:"fernandez",age:25},
  {name:"marcela",surname:"fernandez",age:25},
  {name:"omar",surname:"caster",age:26},
  {name:"luna",surname:"potter",age:30},
  {name:"harry",surname:"potter",age:30},
];

const resultArray = originalArray.reduce((acc, current) => {
  let currentOrder = acc.order;
  const prevItem = acc.result[acc.result.length - 1];
  
  // 首次遍历或当前元素与上一个元素的姓氏、年龄不同时，递增order
  if (!prevItem || prevItem.surname !== current.surname || prevItem.age !== current.age) {
    currentOrder = acc.order + 1;
  }
  
  acc.result.push({ order: currentOrder, ...current });
  acc.order = currentOrder;
  return acc;
}, { order: 0, result: [] }).result;

console.log(resultArray);

代码逻辑说明 #

• 使用Array.reduce()方法遍历数组，通过累加器acc维护两个状态：当前的order计数和结果数组result
• 每次遍历元素时，检查是否为第一个元素，或当前元素的surname和age是否与上一个已处理元素不同
• 满足条件时，将order计数加1；否则沿用当前的order值
• 将包含order字段的新元素推入结果数组，更新累加器状态后继续遍历
• 最终从累加器中提取result字段，得到符合要求的目标数组

内容的提问来源于stack exchange，提问作者juan perez