Javascript将对象数组累积到对象数组

Question

我有一个对象数组:

var myArray = [
    {
        "date" : "03/01/2017",
        "value" : 2
    },  {
        "date" : "04/01/2017",
        "value" : 6
    },  {
        "date" : "05/01/2017",
        "value" : 4
    }
];

我需要累加值并保持同一个数组更新值

结果是这样的

var myArray = [
    {
        "date" : "03/01/2017",
        "value" : 2
    },  {
        "date" : "04/01/2017",
        "value" : 8 //(2+6)
    },  {
        "date" : "05/01/2017",
        "value" : 12 //(2+6+4)
    }
];

我知道这是存在的

[0, 1, 2, 3, 4].reduce(function(accumulator, currentValue, currentIndex, array) {
  return accumulator + currentValue;
});

但是我找不到对象也返回对象的例子

Answer 1

使用Array.prototype.forEach 的this 参数来累积值 - 请参见下面的演示:

var myArray=[{"date":"03/01/2017","value":2},{"date":"04/01/2017","value":6},{"date":"05/01/2017","value":4}];

myArray.forEach(function(e){
  this.count = (this.count || 0) +  e.value;
  e.value = this.count;
},Object.create(null));

console.log(myArray);

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