如何合并对象数组中的重复项并求和特定属性？[副本]

Question

我有这个对象数组：

var arr = [
    {
        name: 'John',
        contributions: 2
    },
    {
        name: 'Mary',
        contributions: 4
    },
    {
        name: 'John',
        contributions: 1
    },
    {
        name: 'Mary',
        contributions: 1
    }
];

…我想合并副本，但求和他们的贡献。结果如下：

var arr = [
    {
        name: 'John',
        contributions: 3
    },
    {
        name: 'Mary',
        contributions: 5
    }
];

我如何用JavaScript实现这一点呢？

Answer 1

您还可以使用linq.js提供的linq框架来完成此操作

下面是我使用linq.js编写的代码，这几乎是sql语句。

null

var arr = [
    {
        name: 'John',
        contributions: 2
    },
    {
        name: 'Mary',
        contributions: 4
    },
    {
        name: 'John',
        contributions: 1
    },
    {
        name: 'Mary',
        contributions: 1
    }
];


var aggregatedObject = Enumerable.From(arr)
        .GroupBy("$.name", null,
                 function (key, g) {
                     return {
                       name: key,
                       contributions: g.Sum("$.contributions")
                     }
        })
        .ToArray();

console.log(aggregatedObject);

html lang-html prettyprint-override"><script src="http://cdnjs.cloudflare.com/ajax/libs/linq.js/2.2.0.2/linq.min.js"></script>

Answer 2

您可以使用一个哈希表并生成一个包含所需总和的新数组。

null

var arr = [{ name: 'John', contributions: 2 }, { name: 'Mary', contributions: 4 }, { name: 'John', contributions: 1 }, { name: 'Mary', contributions: 1 }],
    result = [];

arr.forEach(function (a) {
    if (!this[a.name]) {
        this[a.name] = { name: a.name, contributions: 0 };
        result.push(this[a.name]);
    }
    this[a.name].contributions += a.contributions;
}, Object.create(null));

console.log(result);