javascript - 过滤数组以查找具有项目计数的唯一项目

Question

你好，

我使用以下代码返回唯一的类别列表。

  stadium_cats: function () {
    let stadiums =[
        {"name":"Elland road","category":"football","country":"England"},
        {"name":"Principality stadiums","category":"rugby","country":"Wales"},
        {"name":"Twickenham","category":"rugby","country":"England"},
        {"name":"Eden Park","category":"rugby","country":"New Zealand"}
    ];

    var categories  = stadiums.map(function(obj) {return obj.category});
    categories = categories.filter(function(v,i) {return categories.indexOf(v) == i; });
    return categories;
  }

当我运行上面的代码时，我得到了一组唯一的stadium.category值。

有人可以帮我扩展它，这样我就可以得到一个对象数组，而不是返回一个数组:

[{"name":"football","count":"1"}{"name":"rugby","count":"3"}]

我想要这个名字以及它被推荐的次数？

这可能吗？

非常感谢，戴夫

Answer 1

您可以使用 forEach 循环和对象作为可选参数来完成此操作。

let stadiums = [{"name":"Elland road","category":"football","country":"England"},{"name":"Principality stadiums","category":"rugby","country":"Wales"},{"name":"Twickenham","category":"rugby","country":"England"},{"name":"Eden Park","category":"rugby","country":"New Zealand"}];

var result = [];
stadiums.forEach(function(e) {
  if(!this[e.category]) {
    this[e.category] = {name: e.category, count: 0}
    result.push(this[e.category]);
  }
  this[e.category].count++;
}, {});

console.log(result);