如果需要，对数组进行排序并添加空值

Question

我有一个数组，我想要计数和排序。我怎样才能实现这一目标？我的尝试导致无限循环。

我想要这个阵列

[
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-05", timestamp: "2017-12-05 15:58:25", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-06 10:13:12", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-07 09:38:12", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-08", timestamp: "2017-12-08 09:35:25", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-11", timestamp: "2017-12-11 11:25:31", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-12", timestamp: "2017-12-12 15:05:17", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-13", timestamp: "2017-12-13 11:08:40", …}
{activityId: 201609011024550000, Employee_employeeId: 100, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-15 11:51:33", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-18", timestamp: "2017-12-18 11:04:56", …}
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-18 12:04:56", …}
]

在Date_date上看起来像这个基于/排序的数组

（Date_date：“2017-12-01”不存在，因此值为0，Date_date：“2017-12-06”存在两次，因此值为2）

[0,0,0,0...,1,2,0,1...]

好的，如果创建了新阵列。没有jquery。

编辑：对不起，这是我尝试过的代码循环不停

for(var i = 0; i < a.length; i++){
    for(var j = 0; j <= b.length; j++){
        if(parseInt(a[i].Date_date.substring(8))-1==j){
            var num = b[j];
            b[j] = num+1;
        }
        else{
            var num = b[j];
            b[j] = num+0;
        }
    }
}

Answer 1

首先按日期对数组进行排序，然后根据Date_date创建一个对象查找。然后从排序数组中获取第一个和最后一个日期，并为该月的第一天和该月的最后一天创建日期对象。然后使用while循环，通过检查对象查找直到最后一个日期来添加记录。

var data = [{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-05", timestamp: "2017-12-05 15:58:25"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-06 10:13:12"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-07 09:38:12"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-08", timestamp: "2017-12-08 09:35:25"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-11", timestamp: "2017-12-11 11:25:31"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-12", timestamp: "2017-12-12 15:05:17"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-13", timestamp: "2017-12-13 11:08:40"},{activityId: 201609011024550000, Employee_employeeId: 100, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-15 11:51:33"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-18", timestamp: "2017-12-18 11:04:56"},{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-18 12:04:56"},];

var dateCount = data
   .sort((a,b) => new Date(a.Date_date) - new Date(b.Date_date))
   .reduce((r, o) => {
      r[o.Date_date] = r[o.Date_date] || [];
      r[o.Date_date].push(o)
      return r;
  }, {});

//Get the first date from the sorted array
var date1 = new Date(data[0].Date_date);
var firstDay = new Date(date1.getFullYear(), date1.getMonth(), 2);

//Get the last date from the sorted array
var date2 = new Date(data[data.length - 1].Date_date);
var lastDay = new Date(date2.getFullYear(), date2.getMonth() + 1, 1);

var result = [];
while(firstDay <= lastDay){
  var count = (dateCount[firstDay.toISOString().split('T')[0]] || []).length;
  result.push(count);
  firstDay.setDate(firstDay.getDate() + 1);
}

console.log(result);

Answer 2

首先，您需要获取每个日期出现在数组中的次数。所以我使用data.forEach遍历数组中的每个对象。

请注意，我正在跟踪名为counter的对象中的日期计数。

然后，我使用data.map将数组中的每个对象映射到新数组中的项目。因此，对于data数组中的每个项目，我返回它被观察的次数。

如果你不熟悉它们，你可以阅读更多关于Array#map和Array#forEach的信息。

var data = [
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-05", timestamp: "2017-12-05 15:58:25"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-06 10:13:12"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-06", timestamp: "2017-12-07 09:38:12"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-08", timestamp: "2017-12-08 09:35:25"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-11", timestamp: "2017-12-11 11:25:31"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-12", timestamp: "2017-12-12 15:05:17"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-13", timestamp: "2017-12-13 11:08:40"},
{activityId: 201609011024550000, Employee_employeeId: 100, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-15 11:51:33"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-18", timestamp: "2017-12-18 11:04:56"},
{activityId: 201609011024550000, Employee_employeeId: 4075, projectId: 300000000000000200, Date_date: "2017-12-15", timestamp: "2017-12-18 12:04:56"}
];

var counter = {};

data.forEach(function(item) {
  var date = item.Date_date;
  
  if(!!counter[date]) {
    counter[date]++;
  } else {
    counter[date] = 1;
  }
});

console.log("Date-wise counts: ", counter);

var result = data.map(function(item) {
  return counter[item.Date_date];
});

console.log("Result:", result);