根据两个条件减少javascript中的数组[关闭]答案

【问题标题】：Reduce array in javascript based on two conditions [closed]根据两个条件减少javascript中的数组[关闭]
【发布时间】：2022-01-06 06:05:04
【问题描述】：

假设我们有一个对象数组，例如：

[ 
    { id: 1, time: "2021-05-02 10:12:45.123" },
    { id: 1, time: "2021-05-02 11:12:45.123" },
    { id: 1, time: "2021-05-02 12:12:45.123" },
    { id: 2, time: "2021-05-02 05:12:45.123" },
    { id: 1, time: "2021-05-01 12:12:45.123" },
    { id: 2, time: "2021-05-01 05:12:45.123" },
    { id: 2, time: "2021-05-01 04:12:45.123" },
    { id: 3, time: "2021-05-01 10:12:45.123" },
]

所以我的目的是减少 javascript 中的数组，因此结果是 -> 每天的每个 Id 都有最新的时间，例如：

[ 
    { id: 1, time: "2021-05-02 12:12:45.123" },
    { id: 2, time: "2021-05-02 05:12:45.123" },
    { id: 1, time: "2021-05-01 12:12:45.123" },
    { id: 2, time: "2021-05-01 05:12:45.123" },
    { id: 3, time: "2021-05-01 10:12:45.123" },
]

请你帮忙。提前致谢

【问题讨论】：

标签： javascript arrays group-by reduce

【解决方案1】：

您可以使用reduce轻松实现结果

const arr = [
  { id: 1, time: "2021-05-02 10:12:45.123" },
  { id: 1, time: "2021-05-02 11:12:45.123" },
  { id: 1, time: "2021-05-02 12:12:45.123" },
  { id: 2, time: "2021-05-02 05:12:45.123" },
  { id: 1, time: "2021-05-01 12:12:45.123" },
  { id: 2, time: "2021-05-01 05:12:45.123" },
  { id: 2, time: "2021-05-01 04:12:45.123" },
  { id: 3, time: "2021-05-01 10:12:45.123" },
];

const result = arr.reduce((acc, curr) => {
  if (acc.length && acc[acc.length - 1].id === curr.id) {
    if (new Date(acc[acc.length - 1].time) < new Date(curr.time)) {
      acc[acc.length - 1] = { ...acc[acc.length - 1], ...curr };
    }
  } else acc.push(curr);
  return acc;
}, []);

console.log(result);

【讨论】：