Question

例如我有这个对象数组

const purchases = [
  {
    name: 'a',
    price: 500
  },
  {
    name: 'a',
    price: 1000
  },
  {
    name: 'b',
    price: 500
  },
  {
    name: 'b',
    price: 500
  }
]

如何通过purchases.name有效过滤和计算，创建输出可以像这样

let filteredPurchases = [
  {
    name: 'a',
    price: 1500  
  },
  {
    name: 'b',
    price: 1000  
  }
]

Answer 1

您可以将array#reduce与Object.values()一起使用，根据name值对数据进行分组，并在对象中为同一price添加name，然后提取出来所有的价值观。

const purchases = [ { name: 'a', price: 500 }, { name: 'a', price: 1000 }, { name: 'b', price: 500 }, { name: 'b', price: 500 } ],
      result = Object.values(purchases.reduce((r,{name, price}) => {
        r[name] = r[name] || {name, price : 0};
        r[name].price += price;
        return r;
      },{}));
console.log(result);

Answer 2

您可以使用Array#reduce执行一些简单的操作，并使用对象引用来保留索引。

＆＃13;

const purchases = [{
    name: 'a',
    price: 500
  },
  {
    name: 'a',
    price: 1000
  },
  {
    name: 'b',
    price: 500
  },
  {
    name: 'b',
    price: 500
  }
];

// object for keeping index
const ref = Object.create(null);

let res = purchases
  // iterate over the array
  .reduce((arr, o) => {
    // check index already defined, if defined add price value
    if (o.name in ref) arr[ref[o.name]].price += o.price;
    // if not then define index and insert a new object with all property of object
    else arr[ref[o.name] = arr.length] = Object.assign({}, o);
    // return the array reference
    return arr;
    // set initial value as an array for result
  }, [])

console.log(res);

＆＃13;

Answer 3

＆＃13;

const purchases = [
  {
    name: 'a',
    price: 500
  },
  {
    name: 'a',
    price: 1000
  },
  {
    name: 'b',
    price: 500
  },
  {
    name: 'b',
    price: 500
  }
];
var result = []
function findSum(array, key) {
  let sum = 0;
  array.forEach(function(element) {
    if(key == element.name) {
      sum = sum + element.price;
    }   
  });
  return sum;
}
purchases.forEach(function(element) { 
  let sum = findSum(purchases, element.name);       
  result[element.name] =({name:element.name,price:sum});   
});
console.log("Result obj")
console.log(Object.values(result));

＆＃13;

Answer 4

您可以创建和中间地图以对项目的价格求和，然后迭代它以创建所需的结果：

const purchases = [{
    name: 'a',
    price: 500
  },
  {
    name: 'a',
    price: 1000
  },
  {
    name: 'b',
    price: 500
  },
  {
    name: 'b',
    price: 500
  }
];

const mapped = purchases.reduce((result, item) => {
  if (!result[item.name]) {
    result[item.name] = item.price;
  } else {
    result[item.name] = result[item.name] + item.price;
  }
  return result;
}, {});

const result = Object.keys(mapped).map(key => {
  return {
    name: key,
    price: mapped[key]
  };
});

console.log(result);

如何在Javascript中过滤和计算相同的对象数组值

4 个答案: