计算 JavaScript 对象中属性百分比的变化

Question

我想通过它的先前范围来计算一系列数据的百分比变化。

这是我正在做的一个例子：

下面是一组对象，我需要根据WeekNo 范围的选择来计算displayAd_imp、videoAd_imp 和tv_impbased 属性的百分比变化。

var objArr = [{

    "Title": "July 13 - July 19 2014",
        "displayAd_imp": "3,500",
        "videoAd_imp": "1.5",
        "tv_imp": "0.52",
        "Date": "2014-07-17T00:00:00.000Z",
        "WeekNo": 29
}, {

    "Title": "July 20 - July 26 2014",
        "displayAd_imp": "1,600",
        "videoAd_imp": "2.55",
        "tv_imp": "0.052",
        "Date": "2014-07-24T00:00:00.000Z",
        "WeekNo": 30
}, {

    "Title": "July 27 - Aug 2 2014",
        "displayAd_imp": "1,500",
        "videoAd_imp": "2.1",
        "tv_imp": "0.122",
        "Date": "2014-07-31T00:00:00.000Z",
        "WeekNo": 31
}, {

    "Title": "Aug 3 - Aug 9 2014",
        "displayAd_imp": "1,500",
        "videoAd_imp": "1.99",
        "tv_imp": "0.254",
        "Date": "2014-08-07T00:00:00.000Z",
        "WeekNo": 32
}, {

    "Title": "Aug 10 - Aug 17 2014",
        "displayAd_imp": "1,400",
        "videoAd_imp": "2.0",
        "tv_imp": ".235",
        "Date": "2014-08-14T00:00:00.000Z",
        "WeekNo": 33
}];

在下面的方法中，我试图通过首先过滤具有开始和结束WeekNo 的数据，然后计算该数据的总和来完成此任务。这是一个jsfiddle 工作示例。

function CalcWeekRange(data,begin,end){
    //console.log(data,begin, end);
    var newArr = data.filter(function(item){
        return (item.WeekNo >= begin && item.WeekNo <= end);
    });

    var sumArr = [newArr.reduce(function (acc, x) {
        Object.keys(acc).forEach(function (k) {
        acc[k] += Number(x[k]);
                });
                return acc;
            }, {
                displayAd_imp: 0,
                videoAd_imp: 0,
                tv_imp: 0,
            })];
            console.log(sumArr);
}

我遇到困难的部分是通过获取先前范围的总和然后当前/先前 - 1 来计算该期间的百分比变化。例如，在上面的 jsfiddle 中，我们称为 CalcWeekRange(objArr,32,33);。

displayAd_imp 的百分比变化逻辑是：

Current Weeks(32,33): 1400+1500 = 2900（我们在sumArr有这部分）

前几周（30,31）：1600+1500 = 3100

%Change: (2900/3100-1)*100 = -6.45 （注：允许负数）

其余属性也会发生上述情况。

希望问题和示例清楚，感谢您的宝贵时间！

Answer 1

你的意思是除了你上面的对象数组和代码之外还有这个？

var jCurrent = CalcWeekRange(objArr,32,33);
var jPrevious = CalcWeekRange(objArr,30,31);
var jCurrentDisplay = jCurrent[0].displayAd_imp;
var jPreviousDisplay = jPrevious[0].displayAd_imp;
var result = (jCurrentDisplay/jPreviousDisplay-1)*100;
console.log("result ", result);

在这里调整了你的 jsFiddle：jsFiddle

更新：如果您想根据实际的当前周获得结果，可以通过对上述代码进行以下调整来完成：

Date.prototype.getWeek = function() {
 var firstday = new Date(this.getFullYear(),0,1);
 var today = new Date(this.getFullYear(),this.getMonth(),this.getDate());
 var dayOfYear = ((today - firstday + 86400000)/86400000);
 return Math.ceil(dayOfYear/7)
};

var today = new Date();
var currentWeekNumber = today.getWeek();

var jCurrentDynamic = CalcWeekRange(objArr,currentWeekNumber-1,currentWeekNumber);
var jPreviousDynamic = CalcWeekRange(objArr,currentWeekNumber -3,currentWeekNumber -2);

var jCurrentDisplayDynamic = jCurrentDynamic[0].displayAd_imp;
var jPreviousDisplayDynamic = jPreviousDynamic[0].displayAd_imp;
var resultDynamic = (jCurrentDisplayDynamic/jPreviousDisplayDynamic-1)*100;
console.log("resultDynamic ", resultDynamic);

我已经更新了小提琴并为当前的第 34 周添加了一个对象（只是第 33 周的副本用于测试），所以小提琴将在下周停止工作:)

Updated Demo