如何在对象数组中合并重复项并对特定属性求和？

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
    }
];

...我希望合并重复,但总结他们的贡献.结果如下:

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

我怎么能用JavaScript实现这一目标？

Answer 1

您可以使用哈希表并生成带有总和的新数组.

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);