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javascript - 如何根据日期过滤数据？

问题描述

我有一个数组，

var data = [
    { id: 1, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2017-05-01]" },
    { id: 2, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2018-01-01]" },
    { id: 3, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2019-01-01]" },
    { id: 4, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2017-05-01]" },
    { id: 5, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2018-01-01]" },
    { id: 6, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2019-01-01]" },
    { id: 7, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2018-01-01]" },
    { id: 8, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2019-01-01]" },
    { id: 9, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2017-05-01]" }
    ];
    
    
data.forEach(function(result) {
   console.log(result.jobCategoryWithFromDate);
});

这在控制台中给出了上述结果..

在 foreach 里面，我需要返回jobCategoryWithFromDate最新日期的。

所以预期的结果是，（如下所示）..

ASSIST.. / Assistance [valid from 2019-01-01]
PROF.. / Professional [valid from 2019-01-01]
SEN.. / Senior [valid from 2019-01-01]

以上是预期的结果，没有任何变化，只需要过滤结果并返回jobCategoryWithFromDate具有最新日期的唯一值..

尽管名称重复，但过滤器需要根据日期（最新）处理。

编辑：

我已经接受了答案，但后来我才知道它在所有情况下都不起作用，很抱歉没有完全测试它..

不知道我的解释是否出错，但如果用户名相同，则需要根据日期进行过滤，否则需要显示任何日期的唯一用户。

例如：

    var data = [
        { id: 1, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2017-05-01]" },
        { id: 2, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2018-01-01]" },
        { id: 3, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2019-01-01]" },
        { id: 4, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2017-05-01]" },
        { id: 5, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2018-01-01]" },
        { id: 6, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2019-01-01]" },
        { id: 7, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2018-01-01]" },
        { id: 8, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2019-01-01]" },
        { id: 9, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2017-05-01]" },
        { id: 10, jobCategoryWithFromDate: "Jun.. / Junior  [valid from 2018-01-01]" },
        { id: 11, jobCategoryWithFromDate: "Usr.. / User [valid from 2019-01-01]" },
        { id: 12, jobCategoryWithFromDate: "Man.. / Manager [valid from 2017-05-01]" }
    ];

function extractDate(string){
  return string.match(/[0-9]+-[0-9]+-[0-9]+/g);
}

var result = data.reduce((newestDates, currentItem)=>{
  if (newestDates.length===0) newestDates.push(currentItem);
  else {
    const dateDifference = new Date(extractDate(newestDates[0].jobCategoryWithFromDate)) - new Date(extractDate(currentItem.jobCategoryWithFromDate));
    
    if (dateDifference===0) newestDates.push(currentItem); // push items with the same date as newest found
    else if (dateDifference <= 0) newestDates = [currentItem]; // if item has newer date the original array gets replaced with one containing just this item
    // ignore case dateDifference >= 0 because we do not need to do anything with dates older than the newest found
  }
  return newestDates;
},[]);

console.log(result);

在此代码段中，查看最后三个值，它们具有不同的用户名，但与以前的记录具有相同的日期。

这里的预期结果是我需要获取所有最后三个记录以及以上三个记录，因为它们是不同的用户，比如

ASSIST.. / Assistance [valid from 2019-01-01]
PROF.. / Professional [valid from 2019-01-01]
SEN.. / Senior [valid from 2019-01-01]
Jun.. / Junior  [valid from 2018-01-01]
Usr.. / User [valid from 2019-01-01]
Man.. / Manager [valid from 2017-05-01]

标签： javascript

解决方案

我会先找到最新的日期，然后过滤数组以查找具有此日期的对象。这将只返回日期最高的对象：

var data = [
  { id: 1, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2017-05-01]" },
  { id: 2, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2018-01-01]" },
  { id: 3, jobCategoryWithFromDate: "ASSIST.. / Assistance [valid from 2019-01-01]" },
  { id: 4, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2017-05-01]" },
  { id: 5, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2018-01-01]" },
  { id: 6, jobCategoryWithFromDate: "PROF.. / Professional [valid from 2019-01-01]" },
  { id: 7, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2018-01-01]" },
  { id: 8, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2019-01-01]" },
  { id: 9, jobCategoryWithFromDate: "SEN.. / Senior [valid from 2017-05-01]" }
];

/* Add new property to data objects to store the "valid from" timestamp - Avoids parsing the text twice */
data.forEach(function(element, index, array) {
  var dateText = element.jobCategoryWithFromDate.match(/\[valid from (\d{4}-\d{2}-\d{2})\]$/)[1];
  array[index].fromDateTimestamp = +(new Date(dateText));
});

/* Get the highest value (the latest date) */
var max = data.reduce(function(currentMax, value) {
  return Math.max(currentMax, value.fromDateTimestamp);
}, 0);

/* Filter the data array to only include objects with the latest date */
var newData = data.filter(function(value) {
  return value.fromDateTimestamp === max;
});

console.log(newData);

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