Question

按日期对对象进行分组的最佳方法是什么，并将它们全部添加到创建单个JavaScript对象？我更喜欢代码可读性和较少的代码行而不是性能，因为应用程序不是数据密集型的。此外，在我完成实习后，会有很多人会做出改变。

以下是一些示例数据

[
    {"Timestamp":"Thu, 01 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 01 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 03:57:00 GMT","cp":0,"pc":4},

    {"Timestamp":"Thu, 02 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 02 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 03:57:00 GMT","cp":0,"pc":4}

]

我想从上述数据中创建它。

[ {"Date":"2015-01-01", "cp":4, "pc":12}, {"Date":"2015-01-02", "cp":4, "pc"12} ]

如果您注意到，生成的JavaScript对象是该特定日期所有列的总和，并按日期替换时间戳。

我们已在应用程序中使用moment.js，因此我可以使用它。如果您认为时刻能够以更整洁的方式解决问题，请告诉我。

Answer 1

迭代您的对象数组（$.each()函数可用于迭代任何集合。）
使用UTC方法将ISO格式的日期字符串转换为toISOString()格式。
维护日期的公共数组，以便您可以使用indexOf()方法轻松映射重复的日期位置。

以下是代码：

var arr = [
  {"Timestamp":"Thu, 01 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 01 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
  {"Timestamp":"Thu, 01 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 01 Jan 2015 03:57:00 GMT","cp":0,"pc":4},

  {"Timestamp":"Thu, 02 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 02 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
  {"Timestamp":"Thu, 02 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
  {"Timestamp":"Thu, 02 Jan 2015 03:57:00 GMT","cp":0,"pc":4}
];
var resultArr = [];
var dateArr = [];   

$.each(arr, function () {
// Easiest way to get your required date format
   var date = new Date(this.Timestamp).toISOString().replace(/T/, ' ').split(' ')[0];
   var index = dateArr.indexOf(date);
   if (index == -1) {
       dateArr.push(date);
       var obj = {Date: date, cp: this.cp, pc: this.pc};
       resultArr.push(obj);
   } 
   else {
       resultArr[index].cp += this.cp;
       resultArr[index].pc += this.pc;
   }
});
console.log(resultArr); // [ {"Date":"2015-01-01", "cp":4, "pc":12}, {"Date":"2015-01-02", "cp":4, "pc"12} ]

希望这对你有所帮助。

Answer 2

我相信一个简单的实用程序库，例如Underscore.js或Lodash可以完成这项工作，但是，这看起来像一个简单的旧vanilla Javascript可以自己承担的任务。

查看Array.prototype.map函数，或者更好的是Array.prototype.sort，它接受一个将逻辑应用于给定对象的.Timestamp属性的排序函数。

编辑：类似

yourArray.sort(function(objA, objB){
  return objA.Timestamp > objB.TimeStamp ? -1 : 1;
});

可能会奏效。

编辑：我现在看到你正在尝试合并日期。在这种情况下，我会说Array.prototype.map与Array.prototype.reduce链接在一起可能会导致失败。你也可以（乱七八糟地）使用Array.prototype.filter将给定日期的所有数组推送到一个数组中，依此类推每个日期。

编辑：

那么减少呢？

var thingYouWant = yourArray.reduce(function(summed, current){
    date = changeIntoOnlyDayDate(current.Timestamp);
    var found = false;
    summed.forEach(function(obj){
        if(obj.Timestamp === date){ obj.cp++; found = true;};
    }
    if(!found){summed.push(turnThisDateIntoDesiredObject(date))}

    }
    return summed;
    }, []);

Answer 3

试试这个。

var timeArray=[
    {"Timestamp":"Thu, 01 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 01 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 01 Jan 2015 03:57:00 GMT","cp":0,"pc":4},

    {"Timestamp":"Thu, 02 Jan 2015 00:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 01:57:00 GMT","cp":0,"pc":4},
    {"Timestamp":"Thu, 02 Jan 2015 02:57:00 GMT","cp":2,"pc":2},
    {"Timestamp":"Thu, 02 Jan 2015 03:57:00 GMT","cp":0,"pc":4}
]

var object = {}, resultArray = [];

for (var i = 0; i < timeArray.length; i++) {
    var date = timeArray[i].Timestamp;
    var localDateString = new Date(date).getFullYear() + '-' + (new Date(date).getMonth() + 1) + '-' + new Date(date).getDate();
    if (object[localDateString]) {
        object[localDateString].cp += timeArray[i].cp;
        object[localDateString].pc += timeArray[i].pc;
    } else {
        timeArray[i].Date = localDateString;
        delete timeArray[i].Timestamp;
        object[localDateString] = timeArray[i];
    }
}

for (var prop in object)
    resultArray.push(object[prop]);

console.log(resultArray);

在JavaScript中按日期对DateTime对象进行分组和求和

3 个答案: