Question

在AngularJS / Javascript中我有一个对象数组，这些对象包含一个日期。我想按日期订购这些对象，并将属性添加到具有特定日期时间的最后一个对象。因此，如果2个对象具有相同的日期，我想将属性添加到具有最新时间的属性。如果只有一个对象有一个日期，我想将属性添加到该对象。

一个例子：

input:   var arr = [
          {A: {"Date": "2017-08-14T15:15:00"} B:{}} 
          {A: {"Date": "2017-08-14T16:15:00"} B:{}} //<--- Add attribute to this object 
         ] 

output:  var arr = [
          {A: {"Date": "2017-08-14T15:15:00"} B:{}} 
          {A: {"Date": "2017-08-14T16:15:00"} B:{} C:{"NewAttribute": "true"}} 
         ]

我如何编程呢？最初我在考虑使用for循环来比较所有对象，但我不知道如何实现它。

Answer 1

我希望我理解你想要的东西：

＆＃13;

var arr = [
  {A: {"Date": "2017-08-14T15:15:00"}, B:{}}, // won't get the new property
  {A: {"Date": "2017-08-14T16:12:00"}, B:{}}, // will get the new property
  {A: {"Date": "2017-08-14T15:15:00"}, B:{}}, // will get the new property
  {A: {"Date": "2017-08-14T16:14:00"}, B:{}}, // won't get the new property
  {A: {"Date": "2017-08-14T16:14:00"}, B:{}}  // will get the new property
];

// sort the array by date in descending order
var sorted = arr.sort(({A: { Date: d1 }}, {A: { Date: d2 }}) => new Date(d2).getTime() - new Date(d1).getTime());

// eventually add the new property
sorted.reduce((acc, o) => {
  var date = o.A.Date;
  if (acc !== date) {
    // the date isn't equal to the date of the last item, so it's
    // either the only item with that date
    // or the first (in reversed order) item with that date
    o.C = {"NewAttribute": "true"};
  }
  return date;
}, '');

// reverse the array
var result = sorted.slice().reverse();

console.log(result);

＆＃13;

Answer 2

您可以先使用Array.prototype.sort()按日期对数组进行排序，然后将新属性添加到最后一个元素：

＆＃13;

var arr = [
      {A: {"Date": "2017-08-14T15:15:00"},B: {}},
      {A: {"Date": "2017-08-16T16:15:00"},B: {}},
      {A: {"Date": "2017-08-24T16:15:00"},B: {}},
      {A: {"Date": "2017-08-24T16:15:00"},B: {}, C: {}}
    ],
    alphabetArr = 'abcdefghijklmnopqrstuvwxyz'
      .toLocaleUpperCase()
      .split(''),
    lastElementLength = 0;

// Sort the array
arr.sort(function (a, b) {
  return new Date(b.A.date) - new Date(a.A.date);
});

// Get last element properties length
lastElementLength = Object.keys(arr[arr.length - 1]).length;

// Adds new attribute to last element with the proper name..
arr[arr.length - 1][alphabetArr[lastElementLength]] = {
  "NewAttribute": "true"
};

console.log(arr);

＆＃13;

.as-console-wrapper { max-height: 100% !important; top: 0; }

＆＃13;

将属性添加到数组中的特定对象

2 个答案: