通过方法对数组中的对象进行排序答案

【问题标题】：Sorting an object in an array through a method通过方法对数组中的对象进行排序
【发布时间】：2019-09-07 12:02:16
【问题描述】：

此函数对数组进行排序。首先，应该显示国家等于第二个参数中指定的对象。然后剩下的。但我不明白哪里出了问题？

 
const arr = [
  {  
"name":"BMW",
"price":"55 000",
"country":"Germany",
"certificate":"yes"
  },
  {  
"name":"Mitsubishi",
"price":"93 000", 
"constructor":"Bar John",
"door":"3",
"country":"Japan",
  },
  {  
"name":"Mercedes-benz",
"price":"63 000", 
"country":"Germany",
"certificate":"yes"
  },
  {  
"name":"TOYOTA", 
"price":"48 000", 
"max_people":"7",
"country":"Japan",
"certificate":"yes"
  },
  {  
"name":"Volkswagen",
"price":"36 000", 
"constructor":"Pier Sun",
"country":"Germany",
"certificate":"no"
  },
 ];

 function countries(arr,country){
  let one =  arr.sort(function(item){
return country > item.country;
  });
  return one;
}

console.log(countries(arr,"Japan"));

【问题讨论】：

标签： javascript arrays sorting object methods

【解决方案1】：

您需要将这两个对象与通缉的国家/地区进行比较，然后将此项目移至顶部。

Array#sort 改变数组的顺序。

function countries(array, country) {
    return array.sort(({ country: a }, { country: b }) => (b === country) - (a === country));
}

const array = [{ name: "BMW", price: "55 000", country: "Germany", certificate: "yes" }, { name: "Mitsubishi", price: "93 000", constructor: "Bar John", door: "3", country: "Japan" }, { name: "Mercedes-benz", price: "63 000", country: "Germany", certificate: "yes" }, { name: "TOYOTA", price: "48 000", max_people: "7", country: "Japan", certificate: "yes" }, { name: "Volkswagen", price: "36 000", constructor: "Pier Sun", country: "Germany", certificate: "no" }];

console.log(countries(array, "Japan"));

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【讨论】：

感谢您的精彩回答！我也有同样的问题。为了兼容 IE，我将您的代码调整为：return array.sort(function(a, b) { return (b.country === country) - (a.country === country));

【解决方案2】：

确保sort的回调有两个参数，并稍微改变你的排序逻辑：

 

const arr = [
  {  
"name":"BMW",
"price":"55 000",
"country":"Germany",
"certificate":"yes"
  },
  {  
"name":"Mitsubishi",
"price":"93 000", 
"constructor":"Bar John",
"door":"3",
"country":"Japan",
  },
  {  
"name":"Mercedes-benz",
"price":"63 000", 
"country":"Germany",
"certificate":"yes"
  },
  {  
"name":"TOYOTA", 
"price":"48 000", 
"max_people":"7",
"country":"Japan",
"certificate":"yes"
  },
  {  
"name":"Volkswagen",
"price":"36 000", 
"constructor":"Pier Sun",
"country":"Germany",
"certificate":"no"
  },
 ];

 function countries(arr,country){
  let one =  arr.sort(function(a, b){
return a == country ? -1 : b == country ? 1 : 0;
  });
  return one;
}

console.log(countries(arr,"Japan"));

【讨论】：

【解决方案3】：

Array.sort 中的比较函数应该返回：

值 > 0 表示 a > b
值
值 == 0 表示 a == b

所以最简单的方法就是改成：

let one = arr.sort(function(item) {
    return (country > item.country) ? 1 : -1
});

【讨论】：