将对象数组中具有相同对象 propertyB 的 javascript 对象 propertyA 值求和 [英] Sum javascript object propertyA values with same object propertyB in array of objects

问题描述

如何获取一个 javascript 对象数组，例如:

How would one take a javascript array of objects such as:

my objArr = [
{key:Mon Sep 23 2013 00:00:00 GMT-0400, val:42},
{key:Mon Sep 24 2013 00:00:00 GMT-0400, val:78},
{key:Mon Sep 25 2013 00:00:00 GMT-0400, val:23},
{key:Mon Sep 23 2013 00:00:00 GMT-0400, val:54}]

并通过对值求和来合并重复的键.为了得到这样的东西:

and merge duplicate keys by summing the values. In order to get something like this:

my reducedObjArr = [
{key:Mon Sep 23 2013 00:00:00 GMT-0400, val:96},
{key:Mon Sep 24 2013 00:00:00 GMT-0400, val:78},
{key:Mon Sep 25 2013 00:00:00 GMT-0400, val:23}]

我尝试迭代并添加到一个新数组，但这没有用:

I have tried iterating and adding to a new array, but this didn't work:

var reducedObjArr = [];
var item = null, key = null;
for(var i=0; i<objArr.length; i++) {
   item=objArr[i];
   key = Object.keys(item)[0];
   item=item[key];

   if(!result[key]){
       result[key] = item;
   }else{
       result[key] += item;}
   }a

推荐答案

您应该使用 .key 属性将每个未找到的对象分配给结果.

You should be assigning each object not found to the result with its .key property.

如果找到了，则需要添加它的.val.

If it is found, then you need to add its .val.

var temp = {};
var obj = null;
for(var i=0; i < objArr.length; i++) {
   obj=objArr[i];

   if(!temp[obj.key]) {
       temp[obj.key] = obj;
   } else {
       temp[obj.key].val += obj.val;
   }
}
var result = [];
for (var prop in temp)
    result.push(temp[prop]);

<小时>

此外，部分问题是您重用了 item 变量来引用 .key 的值，因此您丢失了对该对象的引用.

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Also, part of the problem was that you were reusing the item variable to reference the value of .key, so you lost reference to the object.

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