如何获取嵌套数组中所有同名字段的总和？

Question

我试图找到嵌套数组的所有字段值的总和，我不擅长解释这样的东西，我希望下面的代码能让你对我想做的事情有所了解。

数组看起来像这样

data = [
    {
        id: 8434,
        name: listName, 
        data: [
            {name: "a name",
             quantity: 20,
            }
            {name: "another name",
             quantity: 40,
            }
            {name: "another new name",
             quantity: 40,
            }
        ]
    }, 
    {
        id: 54343,
        name: "new list name", 
        data: [
            {name: "a name",
             quantity: 12,
            }
            {name: "another name",
             quantity: 10,
            }
            {name: "another new name",
             quantity: 16,
            }
        ]
    }
]

这就是我希望数据在执行总和后的样子

transformed = [
{name: "a name", quantity: 32},
{name: "another name", quantity: 50},
{name: "another new name", quantity: 56}
]

Answer 1

const transform = (data) => {
  const quantitySum = new Map()
  
  data.forEach(list => {
    list.data.forEach(({ name, quantity }) => {
      if (quantitySum.has(name)) {
        quantitySum.set(name, quantitySum.get(name) + quantity)
      } else {
        quantitySum.set(name, quantity)
      }
    })
  })
  
  return Array.from(quantitySum.entries())
    .map(([name, sum]) => ({
    name,
    quantity: sum
  }))
}

Answer 2

您可以使用 Array.flatMap() 后跟 Array.reduce() 以获得所需的结果。

我们首先调用 .flatMap() 获取所有数据值，然后对这些值调用 .reduce() 以 name.

对每个值求和

这将创建一个对象，每个名称都有一个属性，然后我们调用Object.values()到return到一个数组。

const data = [ { id: 8434, name: 'listName', data: [ { name: "a name", quantity: 20, }, { name: "another name", quantity: 40, }, { name: "another new name", quantity: 40, } ] }, { id: 54343, name: "new list name", data: [ { name: "a name", quantity: 12, }, { name: "another name", quantity: 10, }, { name: "another new name", quantity: 16, } ] } ];

const transformed = Object.values(data.flatMap(({ data }) => data).reduce((acc, { name , quantity }) => { 
    acc[name] = acc[name] || { name, quantity: 0 };
    acc[name].quantity += quantity;
    return acc;
}, {}))

console.log('Transformed:', transformed)

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

Answer 3

只需将它们循环并创建一个新对象..

const data = [
    {
        id: 8434,
        name: 'listName', 
        data: [
            {
                name: "a name",
                quantity: 20,
            },
            {
                name: "another name",
                quantity: 40,
            },
            {
                name: "another new name",
                quantity: 40,
            }
        ]
    }, 
    {
        id: 54343,
        name: "new list name", 
        data: [
            {
                name: "a name",
                quantity: 12,
            },
            {
                name: "another name",
                quantity: 10,
            },
            {
                name: "another new name",
                quantity: 16,
            }
        ]
    }
]


// Logic:
const transformed = []

data.forEach(d => {
    d.data.forEach(item => {
        const exist = transformed.find(t => t.name == item.name)
        if(exist) 
            exist.quantity += item.quantity
        else 
            transformed.push(item)
    })
})

console.log(transformed)

输出：

[
  { name: 'a name', quantity: 32 },
  { name: 'another name', quantity: 50 },
  { name: 'another new name', quantity: 56 }
]

如何获取嵌套数组中所有同名字段的总和？

How to the get the sum of all the field with the same name in a nested array?

javascript

arrays

node.js