通过方法对数组中的对象进行排序

Question

此函数对数组进行排序。首先，应显示国家/地区等于第二个自变量中指定的国家/地区的对象。然后剩下的一切。但是我不明白怎么了？

 
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"));

 

Answer 1

您需要将两个对象与所需的国家/地区进行比较，然后将其移至顶部。

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"));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

确保sort的回调具有两个参数，并稍微更改排序逻辑：

 

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"));

 

Answer 3

Array.sort中的比较函数应返回：

• 值> 0表示a> b
• 值<0表示
• 值== 0表示a == b

所以最简单的方法是将其更改为：

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