将相同的“类别”对象分组

Question

我正在尝试对来自以下位置的原始数据进行分组：

items:
[
    {
        category: "blog",
        id      : "586ba9f3a36b129f1336ed38",
        content : "foo, bar!"
    },
    {
        category: "blog",
        id      : "586ba9f3a36b129f1336ed3c",
        content : "hello, world!"
    },
    {
        category: "music",
        id      : "586ba9a6dfjb129f1332ldab",
        content : "wow, shamwow!"
    },
]

到

[
    {
        category: "blog",
        items:
        [
            {
                id      : "586ba9f3a36b129f1336ed38",
                content : "foo, bar!"
            },
            {
                id      : "586ba9f3a36b129f1336ed3c",
                content : "hello, world!"
            },
        ]
    },
    {
        category: "music",
        items:
        [
            {
                id      : "586ba9a6dfjb129f1332ldab",
                content : "wow, shamwow!"
            }
        ]
    }
]

这样的格式帮助我在前端打印相同的类别数据。

该category字段的内容是动态的，所以我不确定如何将其存储到临时对象并对它们进行排序，有什么想法吗？

（我想不出更好的问题标题，如果您有更好的标题，请编辑。）

Answer 1

您可以Array#reduce一次性完成：

var items = [{"category":"blog","id":"586ba9f3a36b129f1336ed38","content":"foo, bar!"},{"category":"blog","id":"586ba9f3a36b129f1336ed3c","content":"hello, world!"},{"category":"music","id":"586ba9a6dfjb129f1332ldab","content":"wow, shamwow!"}];

var result = items.reduce(function(r, item) {
  var current = r.hash[item.category];
  
  if(!current) {
    current = r.hash[item.category] = { 
      category: item.category,
      items: []
    };
    
    r.arr.push(current);
  }

  current.items.push({
    id: item.id,
    content: item.content
  });
  
  return r;
}, { hash: {}, arr: [] }).arr;
  
console.log(result);

或者 ES6 方式使用Map：

const items = [{"category":"blog","id":"586ba9f3a36b129f1336ed38","content":"foo, bar!"},{"category":"blog","id":"586ba9f3a36b129f1336ed3c","content":"hello, world!"},{"category":"music","id":"586ba9a6dfjb129f1332ldab","content":"wow, shamwow!"}];

const result = [...items.reduce((r, { category, id, content }) => {
  r.has(category) || r.set(category, {
    category,
    items: []
  });
  
  r.get(category).items.push({ id, content });
  
  return r;
}, new Map).values()];
  
console.log(result);