代码之家 › 专栏 › 技术社区 › Kim

对对象数组中的值求和

javascript

-1

Kim · 技术社区 · 7 年前

[
{
    "id": {
    "extId": "112",
    "year": "2000"
    },
    "Count": 1
},
{
    "id": {
    "extId": "113",
    "year": "2001"
    },
    "Count": 446
},
{
    "id": {
    "extId": "115",
    "year": "2000"
    },
    "Count": 742
}, ...
]

我有一个很长的对象数组。我需要根据年份来计算总数。例如,我想要类似[{2000:743},{2001:446},…]的东西。我不知道如何在javascript中继续。我是否应该遍历数组中的每个对象并检查年份,或者是否有一些javascript函数可以简化这一过程。

谢谢

7 回复 | 直到 7 年前

Máté Safranka 7 年前

您可以使用 Array.reduce() :

let countByYear = objects.reduce((acc, next) => {
    acc[next.id.year] = (acc[next.id.year] || 0) + next.Count;
    return acc;
}, {});

注意,这将产生与您的示例不同的结构(因为我对您的问题读得太草率):

然而,我想说这比 [ { 2000: 743 }, { 2001: 446 } ] ,因为在这种情况下,您有一个对象数组,每个对象都有一个键,您无法知道该键是什么,我想这会使迭代它们变得非常困难。

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce

Dusan Jovanov 7 年前

您可以使用reduce:

arr.reduce((result, current) => { result.push({[current.year]: current.Count}); return result }, [])

这将给你这个结构[{2000:743},{2001:44}],你甚至可以 arr.filter(filterFn) 首先,如果只需要筛选特定年份

Nina Scholz 7 年前

你可以使用 Map 并获取对象数组的键/值。

var data = [{ id: { extId: "112", year: "2000" }, Count: 1 }, { id: { extId: "113", year: "2001" }, Count: 446 }, { id: { extId: "115", year: "2000" }, Count: 742 }],
    count = Array.from(
        data.reduce(
            (m, { id: { year }, Count }) => m.set(year, (m.get(year) || 0) + Count),
            new Map
        ),
        ([year, count]) => ({ [year]: count })
    );
    
console.log(count);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Script Host 7 年前

<script>
  var arr=[
{
    "id": {
    "extId": "112",
    "year": "2000"
    },
    "Count": 1
},
{
    "id": {
    "extId": "113",
    "year": "2001"
    },
    "Count": 446
},
{
    "id": {
    "extId": "115",
    "year": "2000"
    },
    "Count": 742
}
];
var result=arr.reduce((result, current) => {
  result.push({[current.id.year]: current.Count});
  return result;
}, []);
console.log(result);

</script>

Ankit Agarwal 7 年前

reduce 将在此处为您完成以下操作:

var arr = [
{
    "id": {
    "extId": "112",
    "year": "2000"
    },
    "Count": 1
},
{
    "id": {
    "extId": "113",
    "year": "2001"
    },
    "Count": 446
},
{
    "id": {
    "extId": "115",
    "year": "2000"
    },
    "Count": 742
},
{
    "id": {
    "extId": "116",
    "year": "2001"
    },
    "Count": 44
}
];

let count = arr.reduce((acc, next) => {
    acc[next.id.year] = (acc[next.id.year] || 0) + next.Count;
    return acc;
}, {});

console.log(count);

Community CDub 5 年前

ES6

你可以使用 reduce() 函数以获得所需的结果。

演示

const data = [{"id": {"extId": "112","year": "2000"},"Count": 1},{"id": {"extId": "113","year": "2001"},"Count": 446},{"id": {"extId": "115","year": "2000"},"Count": 742}];

let result = data.reduce((r, {Count,id: {year}}) => {
  r[year] = (r[year] || 0) + Count;
  return r;
}, {});

console.log([result])

.as-console-wrapper {max-height: 100% !important;top: 0;}

Rahul Bisht 7 年前

var yearCount={};
var temp=[
{
    "id": {
    "extId": "112",
    "year": "2000"
    },
    "Count": 1
},
{
    "id": {
    "extId": "113",
    "year": "2001"
    },
    "Count": 446
},
{
    "id": {
    "extId": "115",
    "year": "2000"
    },
    "Count": 742
}
];
temp.forEach(item=>{
    var val=yearCount[item.id.year];
  if (val){
        yearCount[item.id.year]=val+item.Count;
  }
  else{
    yearCount[item.id.year]=item.Count;
  }
})
console.log(yearCount);