Javascript - 计算多维数组的第一个元素

Question

我有以下代码来提取唯一作者列表的 ID 和用户名。

    let authorsList = await Poem.find({ 'author.id': {$nin: community.busAdmins}}).where('communities').equals(community._id).populate('authors').sort({"author.username": 1});

    let uniqueAuthorsList = [];
    authorsList.forEach(details => {
        if(!uniqueAuthorsList.some(code => code.username == details.author.username)){
            uniqueAuthorsList.push({username: details.author.username, id: details.author.id});
        }
    });

对于这些作者中的每一位，我想计算他们写了多少博客。 到目前为止，我有这个代码：

const counts = {};
        uniqueAuthorsList.forEach((el) => {
        counts[el] = counts[el] ? (counts[el] += 1) : 1;
        });
        console.log(counts);

但这只会返回：

{ '[object Object]': 7 }

如何仅使用数组的第一个元素（用户名）来计算记录，所以我可以返回这样的列表？

Dave: 4
Emily: 7
Mark: 2

Answer 1

创建时将计数放入uniqueAuthorsList中。

let uniqueAuthorsList = [];
authorsList.forEach(details => {
  let author = uniqueAuthorsList.find(code => code.username == details.author.username);
  if (author) {
    author.count++;
  } else {
    uniqueAuthorsList.push({
      username: details.author.username,
      id: details.author.id,
      count: 1
    });
  }
});

您可能只想将uniqueAuthors对象而不是数组。

let uniqueAuthors = {};
authorsList.forEach(details => {
  if (uniqueAuthors[details.author.username]) {
    uniqueAuthors[details.author.username].count++;
  } else {
    uniqueAuthors[details.author.username] = {
      username: details.author.username,
      id: details.author.id,
      count: 1
    };
  }
});