如何按天、周、月对具有时间戳属性的对象进行分组?

问题描述

在 nodejs 应用程序中，我有一个事件对象数组，格式如下:

In a nodejs application, I have an array of event objects formatted as follows:

eventsArray = [ {id: 1, date: 1387271989749 }, {id:2, date: 1387271989760}, ... ]

eventsArray 具有可变长度的 n 个元素，假设我选择时间参考为巴黎时间，我希望能够按天、周或月对元素进行分组:

eventsArray having a variable length of n elements, and supposing I choose time reference to be Paris time, I want to be able to group elements by day, week, or month:

groupedByDay = {

            2012: { ... },
            2013: {
              dayN  : [{id: a0, date: b0}, {id: a1, date: b1}, {id: a2, date: b2 }],
              dayN+1: [{id: a3, date: b3}, {id: a4, date: b4}, {id: a5, date: b5 }],
              ...
                   },
            2014: { ... }

          }

groupedByWeek = {
            2012: { ... }
            2013: {
              weekN: [{id: a0, date: b0}, {id: a1, date: b1}, {id: a2, date: b2 }],
              weekN+1: [{id: a3, date: b3}],
              ....
                  },
             2014: { ... }
                }

groupedByMonth = {
             2012: { ... },
             2013: {
               monthN: [ {id: a0, date: b0 }, {id: a1, b1}, {id: a2, b2}, {id: a3, b3 }],
               monthN+1: [ {id: a4, date: b4 }, {id: a5, b5}, {id: a6, b6}],
               ...
                   },
              2014: { ... }
                 }

在处理 unix 时间戳方面几乎没有经验，我想知道如何做到这一点，或者是否有一个 npm 模块可以让这更容易.

Having very little experience with manipulating unix timestamps, I was wondering how this could be done or if there was an npm module that would make this easier.

推荐答案

这是我的解决方案.请记住，日、周和月是相对于起源而言的，因为纪元:

Here is my solution. Keep in mind that day, week and month are relative to origin, since epoch:

let event = [ {id: 1, date: 1387271989749 }, {id:2, date: 1387271989760} ];

function groupday(value, index, array){
   let byday={};
    let d = new Date(value['date']);
    d = Math.floor(d.getTime()/(1000*60*60*24));
    byday[d]=byday[d]||[];
    byday[d].push(value);
  return byday
}

function groupweek(value, index, array){
  let byweek={};
   let d = new Date(value['date']);
    d = Math.floor(d.getTime()/(1000*60*60*24*7));
    byweek[d]=byweek[d]||[];
    byweek[d].push(value);
  return byweek
}

function groupmonth(value, index, array){
   let bymonth={};
    d = new Date(value['date']);
    d = (d.getFullYear()-1970)*12 + d.getMonth();
    bymonth[d]=bymonth[d]||[];
    bymonth[d].push(value);
  return bymonth
}

console.log('grouped by day', event.map(groupday));
console.log('grouped by week',event.map(groupweek));
console.log('grouped by month',event.map(groupmonth));

注意:对象是分组的，但日、周和月的键是数字的.只有年份的键是人类可读的.

NOTE: Objects are grouped but the keys for day, week and month are in digits. Only the key for year is human readable.

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