javascript - 在 Javascript 中，如何在满足某些条件的情况下查找数组中具有最高值的特定属性的对象

Question

有一个名为 householdArray 的数组，其中填充有两个属性的对象:第一个是 isSelling，其值为 true >或假。第二个是askingPrice，它的值是一个数字。还有另一个名为 buyer 的对象，它有一个带有数值的 budget 属性。

如何在 householdArray 中具有 isSelling === true 的所有对象中找到具有最高 askingPrice 的对象在买家的预算之内吗？

Answer 1

您可以使用过滤器和最小值最大值，但我会利用 Array.prototype.reduce() 在 O(n) 时间内一次性完成这项工作。为了鼓励您使用箭头函数，我将首先向您展示箭头，然后向您展示传统的函数实现。

请注意，我们使用像 {isSelling: true, AskPrice: 0} 这样的对象作为归约操作的初始值。

var buyer = {budget:1000},
household = [{  isSelling: true,
              askingPrice: 500},
             {  isSelling: false,
              askingPrice: 500},
             {  isSelling: true,
              askingPrice: 1000},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: false,
              askingPrice: 1000},
             {  isSelling: true,
              askingPrice: 1200},
             {  isSelling: false,
              askingPrice: 690},
             {  isSelling: true,
              askingPrice: 890},
             {  isSelling: true,
              askingPrice: 1500},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: true,
              askingPrice: 900},
             {  isSelling: true,
              askingPrice: 990},
             {  isSelling: false,
              askingPrice: 990},
             {  isSelling: true,
              askingPrice: 670}
            ],
   result = household.reduce((p,c) => c.isSelling === true          &&
                                      c.askingPrice <= buyer.budget &&
                                      c.askingPrice > p.askingPrice ? c : p,{isSelling: true, askingPrice: 0});
console.log(result);

现在有了传统的函数实现

var buyer = {budget:1000},
household = [{  isSelling: true,
              askingPrice: 500},
             {  isSelling: false,
              askingPrice: 500},
             {  isSelling: true,
              askingPrice: 670},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: false,
              askingPrice: 1000},
             {  isSelling: true,
              askingPrice: 1200},
             {  isSelling: false,
              askingPrice: 690},
             {  isSelling: true,
              askingPrice: 890},
             {  isSelling: true,
              askingPrice: 1500},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: true,
              askingPrice: 900},
             {  isSelling: true,
              askingPrice: 990},
             {  isSelling: false,
              askingPrice: 990},
             {  isSelling: true,
              askingPrice: 1000}
            ],
   result = household.reduce(function(p,c){
                               return c.isSelling === true          &&
                                      c.askingPrice <= buyer.budget &&
                                      c.askingPrice > p.askingPrice ? c : p
                             },{isSelling: true, askingPrice: 0});
console.log(result);

如果您想获取符合我们条件的记录索引，只需将索引参数添加到reduce回调中，并使用初始值“0”，如下所示；

var buyer = {budget:1000},
household = [{  isSelling: false,
              askingPrice: 1500},
             {  isSelling: false,
              askingPrice: 500},
             {  isSelling: true,
              askingPrice: 1000},
             {  isSelling: true,
              askingPrice: 670},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: false,
              askingPrice: 1000},
             {  isSelling: true,
              askingPrice: 1200},
             {  isSelling: false,
              askingPrice: 690},
             {  isSelling: true,
              askingPrice: 890},
             {  isSelling: true,
              askingPrice: 1500},
             {  isSelling: true,
              askingPrice: 790},
             {  isSelling: true,
              askingPrice: 900},
             {  isSelling: true,
              askingPrice: 990},
             {  isSelling: false,
              askingPrice: 990}
            ],
   result = household.reduce(function(p,c,i,a){
                               return  a[p].isSelling === false        ||
                                       a[p].askingPrice > buyer.budget ||
                                       c.isSelling === true            &&
                                       c.askingPrice <= buyer.budget   &&
                                       c.askingPrice > a[p].askingPrice ? i : p;  
                             },0);
result = household[result].isSelling === true && household[result].askingPrice <= buyer.budget ? result : -1;
console.log(result);