Question

const data = { 
  "orders" : [ 
    { "items" : {"count":3} },  
    { "items" : {"count":1} },  
    { "items" : {"count":2} } 
  ]
}
let total = 0
data.orders.map((order) => order.items.map((item) => (total += item.count)))
console.log(total)

有没有更聪明的方法，我可以说console.log(someoperation(data))？

Answer 1

您的工作原理，但您也可以使用数组.reduce方法：

const data = { 
  "orders" : [ 
    { "items" : {"count":3} },  
    { "items" : {"count":1} },  
    { "items" : {"count":2} } 
  ]
}

const total = data.orders.reduce((cnt, item) => { return cnt+item.items.count; }, 0)

console.log(total)

编辑：

此外，如果你有lodash，这更容易：

const total = _.sumBy(data.orders, x => x.items.count); // evaluates to 6

Answer 2

您可以使用嵌套的destructuring assignment作为计数值。

var data = { orders: [{ items: { count: 3 } }, { items: { count: 1 } }, { items: { count: 2 } }] },
    total = data.orders.reduce((s, { items: { count } }) => s + count, 0);

console.log(total);

使用对象进行单个调用的函数

const getCount = ({ orders }) => orders.reduce((s, { items: { count } }) => s + count, 0);

var data = { orders: [{ items: { count: 3 } }, { items: { count: 1 } }, { items: { count: 2 } }] };

console.log(getCount(data));

Answer 3

将它包装在带有params的函数中：

function getTotal(startVal) {
  var total = startVal;
  data.orders.map((order) => order.items.map((item) => (total += item.count)))  
  const data = { 
    "orders" : [ 
      { "items" : {"count":3} },  
      { "items" : {"count":1} },  
      { "items" : {"count":2} } 
    ]
  }
  return total;
}

console.log(getTotals(0));

巧妙地添加嵌套属性的方法？

3 个答案: