如何从对象返回值？

Question

有一个接受数组参数的函数。对我来说，通过符号"-“从行中的对象中推导出值是必要的。例如：“宝马-55 000-德国-高度”，“三菱-93 000-酒吧约翰-3-日本”，“梅赛德斯-奔驰-63 000-德国-高度”。错误在哪里？

const car = [
  {  
    "name":"BMW",
    "price":"55 000",
    "country":"Germany",
    "security":"Hight"
  },
  {  
    "name":"Mitsubishi",
    "price":"93 000", 
    "constructor":"Bar John",
    "door":"3",
    "country":"Japan",
  },
  {  
    "name":"Mercedes-benz",
    "price":"63 000", 
    "country":"Germany",
    "security":"Hight"
  }
 ];


function joinArr(car){
  return Object.values(car).forEach(function(){
     return  car.join("-")      
   });  
}

Answer 1

您可以使用map遍历数组。使用Object.values将对象转换为数组。

​

const car = [{"name":"BMW","price":"55 000","country":"Germany","security":"Hight"},{"name":"Mitsubishi","price":"93 000","constructor":"Bar John","door":"3","country":"Japan"},{"name":"Mercedes-benz","price":"63 000","country":"Germany","security":"Hight"}];

function joinArr(car) {
  return car.map(o => Object.values(o).join("-"));
}

var result = joinArr(car);

console.log(result);

​

Answer 2

car不是一个对象，而是一个对象数组。您可能希望映射它(并将car重命名为cars以避免混淆)：

 function joinCars(cars) {
   return cars.map(function(car) {
     return Object.values(car).join("-");
   });
 }

Answer 3

forEach不返回任何内容-只需使用join

function joinArr(car){
    return Object.values(car).join("-");
}

要对整个数组执行此操作并获取字符串数组，请使用map。还可以考虑重命名参数：

​

const car = [
  {  
"name":"BMW",
"price":"55 000",
"country":"Germany",
"security":"Hight"
  },
  {  
"name":"Mitsubishi",
"price":"93 000", 
"constructor":"Bar John",
"door":"3",
"country":"Japan",
  },
  {  
"name":"Mercedes-benz",
"price":"63 000", 
"country":"Germany",
"security":"Hight"
  }
 ];


const joinArr = cars => cars.map(car => Object.values(car).join("-"));

console.log(joinArr(cars));

​