将对象数组与内部字符串数组 javascript 分组

Question

我有一个对象数组，如下所示 -

const books = [
  {
    name:"abc",
    isbn: 123,
    tags: ["tagA","tagB","tagC"]
  },
  {
    name:"xyz",
    isbn: 456,
    tags: ["tagB","tagC"]
  },
  {
    name:"pqr",
    isbn: 456,
    tags: ["tagB"]
  }
];

我想根据每个对象的 tags 对其进行分组，并将匹配的对象推送到字符串数组的 tags 值中。我的预期输出应该是一个以分组值作为键的对象，该值应该是匹配值的数组。

我的预期输出是-

const expected = {
    "tagA" : [
     {
         name:"abc",
       isbn: 123,  
     },
  ],
    "tagB" : [
     {
         name:"abc",
       isbn: 123,  
     },
     {
         name:"xyz",
       isbn: 456,  
     },
     {
         name:"pqr",
       isbn: 456,  
     },
  ],
    "tagC" : [
      {
         name:"abc",
       isbn: 123,  
     },
     {
         name:"xyz",
       isbn: 456,  
     },
  ],
}

Answer 1

键值分组也有类似问题；因为你想根据数组的键值进行分组，你可以这样做：

const books = [
  {
    name:"abc",
    isbn: 123,
    tags: ["tagA","tagB","tagC"]
  },
  {
    name:"xyz",
    isbn: 456,
    tags: ["tagB","tagC"]
  },
  {
    name:"pqr",
    isbn: 456,
    tags: ["tagB"]
  }
];

let grouped = {};

books.forEach((book)=>{

 book.tags.forEach(tag=>{
   if(!grouped[tag]) grouped[tag] = [{name:book.name,isbn:book.isbn}]
   else grouped[tag].push({name:book.name,isbn:book.isbn})
 })

})

console.log(grouped)

Answer 2

这是一个非常标准的 'group by'，带有一个额外的循环以将每个元素添加到多个组中。

此处使用destructuring to isolate the tags array from the rest of the book object, iterating over each tag creating a property in the result using logical nullish assignment (??=) if it doesn't already exist, and then pushing a clone of each book using spread syntax

const books = [{ name: "abc", isbn: 123, tags: ["tagA", "tagB", "tagC"] }, { name: "xyz", isbn: 456, tags: ["tagB", "tagC"] }, { name: "pqr", isbn: 456, tags: ["tagB"] }];

const result = {};
for (const { tags, ...book } of books) {
  for (const tag of tags) {
    (result[tag] ??= []).push({...book});
  }
}

console.log(result);

将对象数组与内部字符串数组 javascript 分组

group array of objects with inner array of strings javascript

javascript

arrays

group