Javascript根据条件减少到组对象

Question

我有以下数据:

var foo = [
    {'MonthNo' : 03, 'CustomerTypeID' : 1 , 'TotalSales' : 45 },
    {'MonthNo' : 03, 'CustomerTypeID' : 2 , 'TotalSales' : 64 },
    {'MonthNo' : 03, 'CustomerTypeID' : 4 , 'TotalSales' : 89 },
    {'MonthNo' : 03, 'CustomerTypeID' : 5 , 'TotalSales' : 42 },
    {'MonthNo' : 04, 'CustomerTypeID' : 1 , 'TotalSales' : 66 },
    {'MonthNo' : 04, 'CustomerTypeID' : 2 , 'TotalSales' : 78 },
    {'MonthNo' : 04, 'CustomerTypeID' : 5 , 'TotalSales' : 20 },
    {'MonthNo' : 04, 'CustomerTypeID' : 6 , 'TotalSales' : 10 }
];

我想把这个转换成下面的

{'MonthNo' : 03, 'CustomerTypeID' : 1 , 'TotalSales' : 198 },
{'MonthNo' : 03, 'CustomerTypeID' : 5 , 'TotalSales' : 42 },
{'MonthNo' : 04, 'CustomerTypeID' : 1 , 'TotalSales' : 144 },
{'MonthNo' : 04, 'CustomerTypeID' : 5 , 'TotalSales' : 20 },
{'MonthNo' : 04, 'CustomerTypeID' : 6 , 'TotalSales' : 10 }

对于每个 MonthNo，除了 CustomerTypeID 5 和 6 之外，我想将 TotalSales 值相加。例如:CustomerTypeID 1、2、4 的 MonthNo 03，它们的 TotalSales 值总和为 198。类似地，对于 MonthNo 04，CustomerTypeID 1 和 2 的 TotalSales 值加起来为 144。

我试过使用reduce函数

var result = foo.reduce(function(obj,item){
    // code here
},{});

但是，我无法将它们分开以获得所需的结果。任何帮助将不胜感激。

Answer 1

您可以检查特殊情况并使用哈希表来引用正确的对象进行计数。

var foo = [{ MonthNo: '03', CustomerTypeID: 1, TotalSales: 45 }, { MonthNo: '03', CustomerTypeID: 2, TotalSales: 64 }, { MonthNo: '03', CustomerTypeID: 4, TotalSales: 89 }, { MonthNo: '03', CustomerTypeID: 5, TotalSales: 42 }, { MonthNo: '04', CustomerTypeID: 1, TotalSales: 66 }, { MonthNo: '04', CustomerTypeID: 2, TotalSales: 78 }, { MonthNo: '04', CustomerTypeID: 5, TotalSales: 20 }, { MonthNo: '04', CustomerTypeID: 6, TotalSales: 10 }],
    result = foo.reduce(function (hash) {
        return function (r, a) {
            var cType = [5, 6].indexOf(a.CustomerTypeID) === -1 ? 1 : a.CustomerTypeID,
                key = [a.MonthNo, cType].join('|');

            if (!hash[key]) {
                hash[key] = { MonthNo: a.MonthNo, CustomerTypeID: cType, TotalSales: 0 };
                r.push(hash[key]);
            }
            hash[key].TotalSales += a.TotalSales;
            return r;
        }
    }(Object.create(null)), []);
 
console.log(result);

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