javascript - 如何从数组中过滤特定属性并将其存储到变量中

Question

我有一个数据数组如下:

var arr = [{
    "Sports" : "Hockey",
    "Country" : "AUS",
    "Players" : 11
},{
    "Sports" : "Football",
    "Country" : "Eng",
    "Players" : 11
},{
    "Sports" : "Tennis",
    "Country" : "AUS",
    "Players" : 11
},{
    "Sports" : "Cricket",
    "Country" : "Ind",
    "Players" : 11
},{
    "Sports" : "Gymnastic",
    "Country" : "Russia",
    "Players" : 11
},{
    "Sports" : "Gym",
    "Country" : "AUS",
    "Players" : 11
}];

我想创建一个对象数组，我只想在上面的数组中使用国家/地区的唯一数据。在这种情况下，我应该得到类似的东西:

var country = [
    { AUS: "" },
    { Eng :"" },
    { Ind : "" },
    { Russia :"" }
];

然后我可以添加我自己的属性，比如 capital:

var country = [{
    AUS: "",
    capital : "Canbara"
}, {
    Eng :"",
    capital : "London"
}, {
    Ind : "",
    capital : "Delhi"
}, {
    Russia :"",
    capital : "Masco"
}];

谁能帮我实现这个目标？

这是我目前尝试过的:

var result = [];
array.forEach(function(e) {
    result.push(this[e.Country]);
}, {});

我卡在这里了。

Answer 1

您可以使用map 方法接受回调 提供的函数。

此外，使用 Set ES6 feature 来删除重复项。

Set 对象允许您存储任何类型的唯一 值，无论是原始 值还是对象 引用资料。

var arr = [{ "Sports" : "Hockey", "Country" : "AUS", "Players" : 11 },{ "Sports" : "Football", "Country" : "Eng", "Players" : 11 },{ "Sports" : "Tennis", "Country" : "AUS", "Players" : 11 },{ "Sports" : "Cricket", "Country" : "Ind", "Players" : 11 },{ "Sports" : "Gymnastic", "Country" : "Russia", "Players" : 11 },{ "Sports" : "Gym", "Country" : "AUS", "Players" : 11 }];
arr=[...new Set(arr.map(function(item){
  return item.Country;
}))].map(function(item){
  return {[item]:""};
});
console.log(arr);

另一种解决方案是使用arrow 函数。

var arr = [{ "Sports" : "Hockey", "Country" : "AUS", "Players" : 11 },{ "Sports" : "Football", "Country" : "Eng", "Players" : 11 },{ "Sports" : "Tennis", "Country" : "AUS", "Players" : 11 },{ "Sports" : "Cricket", "Country" : "Ind", "Players" : 11 },{ "Sports" : "Gymnastic", "Country" : "Russia", "Players" : 11 },{ "Sports" : "Gym", "Country" : "AUS", "Players" : 11 }];
arr=[...new Set(arr.map(a => a.Country))].map(a=> ({[a] : ""}));
console.log(arr);