函数中的条件选择答案

【问题标题】：Conditional selecting in function函数中的条件选择
【发布时间】：2019-01-05 12:51:51
【问题描述】：

我有以下带有餐厅订单的对象。

   var obj = {
      orders: [
        null,
        {
          date: "2018-07-09 10:07:18",
          orderVerified : true,
          item: [
            {
              name: "apple juice",
              price: 3.9,
              quantity: 1,
              isDrink: true 
            },
            {
              name: "Hawaii pizza",
              price: 7,
              quantity: 2,
              isDrink: false
            }
          ]
        },
        {
          date: "2018-07-09 10:07:30",
          orderVerified : false,
          item: [
            {
              name: "Warmer Topfenstrudel",
              price: 3.9,
              quantity: 1,
              isDrink: false
            }
          ]
        },
        {
          date: "2018-07-09 15:07:18",
          orderVerified : true,
          item: [
            {
              name: "Coca Cola 2 l",
              price: 12.9,
              quantity: 3,
              isDrink:true
            }
          ]
        },
        {
          date: "2018-06-13 10:07:18",
          orderVerified : true,
          item: [
            {
              name: "Wiener Schnitzel vom Schwein",
              price: 9.9,
              quantity: 2,
              isDrink: false
            }
          ]
        }
      ]
    };

如果 isDrink 的值为 true，我想总结商品的价格 * 商品数量。我试过使用这个函数，它得到所有项目的总数。但我可以检查 isDrink 是真是假，但我如何总结饮料价格 * 数量？

 fullTotal: function(arr) {
    if (arr!=''){
    return arr.reduce((sum, order) => {
      return sum + order.item.reduce((itemSum, item) => (
        itemSum + (item.price * item.quantity)
      ), 0)
    },0)}
    else {return 0}
  },

请给我一些建议。谢谢！

【问题讨论】：

标签： javascript arrays json vue.js

【解决方案1】：

试试这个

fullTotal: function(arr) {
    if (arr!=''){
    return arr.reduce((sum, order) => {
      return sum + order.item.reduce((itemSum, item) => (
        itemSum + item.isDrink ? (item.price * item.quantity) : 0
      ), 0)
    },0)}
    else {return 0}
  },

【讨论】：

【解决方案2】：

你必须：

根据您的情况从null 值中过滤数组
从非饮料中过滤项目 [property isDrink]

var obj = {
  orders: [
    null,
    {
      date: "2018-07-09 10:07:18",
      orderVerified: true,
      item: [{
          name: "apple juice",
          price: 3.9,
          quantity: 1,
          isDrink: true
        },
        {
          name: "Hawaii pizza",
          price: 7,
          quantity: 2,
          isDrink: false
        }
      ]
    },
    {
      date: "2018-07-09 10:07:30",
      orderVerified: false,
      item: [{
        name: "Warmer Topfenstrudel",
        price: 3.9,
        quantity: 1,
        isDrink: false
      }]
    },
    {
      date: "2018-07-09 15:07:18",
      orderVerified: true,
      item: [{
        name: "Coca Cola 2 l",
        price: 12.9,
        quantity: 3,
        isDrink: true
      }]
    },
    {
      date: "2018-06-13 10:07:18",
      orderVerified: true,
      item: [{
        name: "Wiener Schnitzel vom Schwein",
        price: 9.9,
        quantity: 2,
        isDrink: false
      }]
    }
  ]
};

function fullTotal(arr) {
  if (arr != '') {
    return arr.filter(order => order != null).reduce((sum, order) => {
      return sum + order.item.filter(item => item.isDrink).reduce((itemSum, item) => (
        itemSum + (item.price * item.quantity)
      ), 0)
    }, 0)
  } else {
    return 0
  }
}

console.log(fullTotal(obj.orders));

【讨论】：

这就是我想要的。谢谢！

【解决方案3】：

您可以添加对数组的检查并检查所需的对象和isDrink。然后返回总和

var obj = { orders: [null, { date: "2018-07-09 10:07:18", orderVerified: true, item: [{ name: "apple juice", price: 3.9, quantity: 1, isDrink: true }, { name: "Hawaii pizza", price: 7, quantity: 2, isDrink: false }] }, { date: "2018-07-09 10:07:30", orderVerified: false, item: [{ name: "Warmer Topfenstrudel", price: 3.9, quantity: 1, isDrink: false }] }, { date: "2018-07-09 15:07:18", orderVerified: true, item: [{ name: "Coca Cola 2 l", price: 12.9, quantity: 3, isDrink: true }] }, { date: "2018-06-13 10:07:18", orderVerified: true, item: [{ name: "Wiener Schnitzel vom Schwein", price: 9.9, quantity: 2, isDrink: false }] }] },
    fullTotal = function (array) {
        return Array.isArray(array)
            ? array.reduce((sum, o) => o && Array.isArray(o.item)
                ? o.item.reduce((s, { price, quantity, isDrink }) => s + (isDrink && price * quantity), sum)
                : sum, 0)
            : 0;
    };

console.log(fullTotal(obj.orders));

【讨论】：