对一组对象进行分组并添加时间属性[重复]答案

【问题标题】：Group an array of objects and add the time attribute [duplicate]对一组对象进行分组并添加时间属性[重复]
【发布时间】：2021-03-10 21:33:07
【问题描述】：

我有一个由用户输入填充的自定义对象数组。数组如下所示：

let array = [
  {Course: "Design", Hours: "01:00:00", Week: "1"}, 
  {Course: "Design", Hours: "01:00:00", Week: "3"}, 
  {Course: "Design", Hours: "01:00:00", Week: "2"}, 
  {Course: "Design", Hours: "01:00:00", Week: "1"}, 
  {Course: "Design", Hours: "01:00:00", Week: "2"}
]

我需要修改这个数组，以便计算同一周的所有小时数，并将值按照周的顺序放置在数组中。我想要的结果是这样的：

let newArray = [
  {Course: "Design", Hours: "02:00:00", Week: "1"}, 
  {Course: "Design", Hours: "02:00:00", Week: "2"},
  {Course: "Design", Hours: "01:00:00", Week: "3"},  
]

所以基本上我需要同时排序和计算总和。

【问题讨论】：

标签： javascript arrays sorting datetime reduce

【解决方案1】：

您可以使用moment.js 来获取时间字符串的总和。

要按周对项目进行分组，您可以使用.reduce。

最后，要按Week 对项目进行排序，请使用.sort：

let array = [
  {Course: "Design", Hours: "01:00:00", Week: "1"}, 
  {Course: "Design", Hours: "01:00:00", Week: "3"}, 
  {Course: "Design", Hours: "01:00:00", Week: "2"}, 
  {Course: "Design", Hours: "01:00:00", Week: "1"}, 
  {Course: "Design", Hours: "01:00:00", Week: "2"}
];

const addTwoTimeStrs = (a, b) => {
  let sum = moment.duration(a).add(moment.duration(b));
  sum = moment.utc(sum.asMilliseconds()).format("HH:mm:ss");
  return sum;
}

const arr = Object.values(
  array.reduce((acc,item) => {
    const { Hours: hours, Week: week } = item;
    const weekItem = acc[week];
    acc[week] = weekItem
      ? { ...weekItem, Hours: addTwoTimeStrs(weekItem.Hours,hours) }
      : item;
    return acc;
  }, {})
);

const res = arr.sort((a,b) => Number(a.Week) - Number(b.Week));

console.log(res.map(e => e.Hours));

&lt;script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js" integrity="sha512-qTXRIMyZIFb8iQcfjXWCO8+M5Tbc38Qi5WzdPOYZHIlZpzBHG3L3by84BBBOiRGiEb7KKtAOAs5qYdUiZiQNNQ==" crossorigin="anonymous"&gt;&lt;/script&gt;

【讨论】：

谢谢。如果我只想要一个小时值的数组，需要做哪些更改？像这样：让小时 = [02:00:00, 02:00:00, 01:00:00]？
@egx 欢迎您。如果解决了问题，请点赞并将答案标记为解决方案。关于您的问题，您可以使用.map，如下所示：res.map(e => e.Hours)
我会将其标记为已解决，但它似乎适用于地图。当我使用 console.log() res 时，我仍然得到一组对象。我只需要一个包含 Hours 值的数组。
@egx 答案已更新